diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java
index d02a76f84cf..0090e24d06c 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/AsmUtil.java
@@ -195,7 +195,7 @@ public class AsmUtil {
         if (functionDescriptor.getModality() == Modality.FINAL && !(functionDescriptor instanceof ConstructorDescriptor)) {
             DeclarationDescriptor containingDeclaration = functionDescriptor.getContainingDeclaration();
             if (!(containingDeclaration instanceof ClassDescriptor) ||
-                ((ClassDescriptor) containingDeclaration).getKind() != ClassKind.TRAIT) {
+                ((ClassDescriptor) containingDeclaration).getKind() != ClassKind.INTERFACE) {
                 flags |= ACC_FINAL;
             }
         }
@@ -264,7 +264,7 @@ public class AsmUtil {
 
     private static int innerAccessFlagsForModalityAndKind(@NotNull ClassDescriptor innerClass) {
         switch (innerClass.getKind()) {
-            case TRAIT:
+            case INTERFACE:
                 return ACC_ABSTRACT | ACC_INTERFACE;
             case ENUM_CLASS:
                 return ACC_FINAL | ACC_ENUM;
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/CollectionStubMethodGenerator.kt b/compiler/backend/src/org/jetbrains/kotlin/codegen/CollectionStubMethodGenerator.kt
index 215fffa84f3..03730eff4d2 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/CollectionStubMethodGenerator.kt
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/CollectionStubMethodGenerator.kt
@@ -216,13 +216,13 @@ class CollectionStubMethodGenerator(
     private fun generateMethodStub(signature: JvmMethodSignature, synthetic: Boolean) {
         // TODO: investigate if it makes sense to generate abstract stubs in traits
         var access = ACC_PUBLIC
-        if (descriptor.getKind() == ClassKind.TRAIT) access = access or ACC_ABSTRACT
+        if (descriptor.getKind() == ClassKind.INTERFACE) access = access or ACC_ABSTRACT
         if (synthetic) access = access or ACC_SYNTHETIC
 
         val asmMethod = signature.getAsmMethod()
         val genericSignature = if (synthetic) null else signature.getGenericsSignature()
         val mv = v.newMethod(JvmDeclarationOrigin.NO_ORIGIN, access, asmMethod.getName(), asmMethod.getDescriptor(), genericSignature, null)
-        if (descriptor.getKind() != ClassKind.TRAIT) {
+        if (descriptor.getKind() != ClassKind.INTERFACE) {
             mv.visitCode()
             AsmUtil.genThrow(InstructionAdapter(mv), "java/lang/UnsupportedOperationException", "Mutating immutable collection")
             FunctionCodegen.endVisit(mv, "built-in stub for $signature", null)
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java
index 2db46ec524c..4ced0a47419 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java
@@ -333,7 +333,7 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
         ClassContext objectContext = context.intoAnonymousClass(descriptor, this, OwnerKind.IMPLEMENTATION);
         new ImplementationBodyCodegen(declaration, objectContext, classBuilder, state, getParentCodegen()).generate();
 
-        if (declaration instanceof JetClass && ((JetClass) declaration).isTrait()) {
+        if (declaration instanceof JetClass && ((JetClass) declaration).isInterface()) {
             Type traitImplType = state.getTypeMapper().mapTraitImpl(descriptor);
             ClassBuilder traitImplBuilder = state.getFactory().newVisitor(TraitImpl(declaration, descriptor), traitImplType, declaration.getContainingFile());
             ClassContext traitImplContext = context.intoAnonymousClass(descriptor, this, OwnerKind.TRAIT_IMPL);
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionCodegen.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionCodegen.java
index 499329d17eb..3b994d6b0fe 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/FunctionCodegen.java
@@ -568,7 +568,7 @@ public class FunctionCodegen {
 
         if (kind != OwnerKind.TRAIT_IMPL &&
             contextClass instanceof ClassDescriptor &&
-            ((ClassDescriptor) contextClass).getKind() == ClassKind.TRAIT) {
+            ((ClassDescriptor) contextClass).getKind() == ClassKind.INTERFACE) {
             return;
         }
 
@@ -812,7 +812,7 @@ public class FunctionCodegen {
                         }
 
                         String internalName = typeMapper.mapType(toClass).getInternalName();
-                        if (toClass.getKind() == ClassKind.TRAIT) {
+                        if (toClass.getKind() == ClassKind.INTERFACE) {
                             iv.invokeinterface(internalName, delegateToMethod.getName(), delegateToMethod.getDescriptor());
                         }
                         else {
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java
index 9e8828a77ad..e9dc8a2d2a2 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java
@@ -126,7 +126,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
             if (jetClass.hasModifier(JetTokens.ABSTRACT_KEYWORD)) {
                 isAbstract = true;
             }
-            if (jetClass.isTrait()) {
+            if (jetClass.isInterface()) {
                 isAbstract = true;
                 isInterface = true;
             }
@@ -315,7 +315,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
 
         List<JetDelegationSpecifier> delegationSpecifiers = myClass.getDelegationSpecifiers();
 
-        if (myClass instanceof JetClass && ((JetClass) myClass).isTrait()) {
+        if (myClass instanceof JetClass && ((JetClass) myClass).isInterface()) {
             return;
         }
 
@@ -437,13 +437,13 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
         KotlinBuiltIns builtIns = getBuiltIns(descriptor);
         if (!isSubclass(descriptor, builtIns.getCollection())) return;
 
-        int access = descriptor.getKind() == ClassKind.TRAIT ?
+        int access = descriptor.getKind() == ClassKind.INTERFACE ?
                      ACC_PUBLIC | ACC_ABSTRACT :
                      ACC_PUBLIC;
         if (CodegenUtil.getDeclaredFunctionByRawSignature(descriptor, Name.identifier("toArray"), builtIns.getArray()) == null) {
             MethodVisitor mv = v.newMethod(NO_ORIGIN, access, "toArray", "()[Ljava/lang/Object;", null, null);
 
-            if (descriptor.getKind() != ClassKind.TRAIT) {
+            if (descriptor.getKind() != ClassKind.INTERFACE) {
                 InstructionAdapter iv = new InstructionAdapter(mv);
                 mv.visitCode();
 
@@ -458,7 +458,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
         if (!isGenericToArrayPresent()) {
             MethodVisitor mv = v.newMethod(NO_ORIGIN, access, "toArray", "([Ljava/lang/Object;)[Ljava/lang/Object;", null, null);
 
-            if (descriptor.getKind() != ClassKind.TRAIT) {
+            if (descriptor.getKind() != ClassKind.INTERFACE) {
                 InstructionAdapter iv = new InstructionAdapter(mv);
                 mv.visitCode();
 
@@ -1394,7 +1394,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
     private boolean ignoreIfTraitOrAnnotation() {
         if (myClass instanceof JetClass) {
             JetClass aClass = (JetClass) myClass;
-            if (aClass.isTrait()) {
+            if (aClass.isInterface()) {
                 return true;
             }
             if (aClass.isAnnotation()) {
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/JvmCodegenUtil.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/JvmCodegenUtil.java
index 7fcbc6bfb53..328ef286f21 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/JvmCodegenUtil.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/JvmCodegenUtil.java
@@ -59,7 +59,7 @@ public class JvmCodegenUtil {
     public static boolean isInterface(DeclarationDescriptor descriptor) {
         if (descriptor instanceof ClassDescriptor) {
             ClassKind kind = ((ClassDescriptor) descriptor).getKind();
-            return kind == ClassKind.TRAIT || kind == ClassKind.ANNOTATION_CLASS;
+            return kind == ClassKind.INTERFACE || kind == ClassKind.ANNOTATION_CLASS;
         }
         return false;
     }
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/MemberCodegen.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/MemberCodegen.java
index f1a59a0fadf..2084afdac6e 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/MemberCodegen.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/MemberCodegen.java
@@ -200,7 +200,7 @@ public abstract class MemberCodegen<T extends JetElement/* TODO: & JetDeclaratio
         ClassContext classContext = parentContext.intoClass(descriptor, OwnerKind.IMPLEMENTATION, state);
         new ImplementationBodyCodegen(aClass, classContext, classBuilder, state, parentCodegen).generate();
 
-        if (aClass instanceof JetClass && ((JetClass) aClass).isTrait()) {
+        if (aClass instanceof JetClass && ((JetClass) aClass).isInterface()) {
             Type traitImplType = state.getTypeMapper().mapTraitImpl(descriptor);
             ClassBuilder traitImplBuilder = state.getFactory().newVisitor(TraitImpl(aClass, descriptor), traitImplType, aClass.getContainingFile());
             ClassContext traitImplContext = parentContext.intoClass(descriptor, OwnerKind.TRAIT_IMPL, state);
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java
index 6c0e8e664a2..c860d078e6d 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java
@@ -443,7 +443,7 @@ public abstract class StackValue {
         // Coerce this/super for traits to support traits with required classes.
         // Coerce explicit 'this' for the case when it is smart cast.
         // Do not coerce for other classes due to the 'protected' access issues (JVMS 7, 4.9.2 Structural Constraints).
-        boolean coerceType = descriptor.getKind() == ClassKind.TRAIT || (isExplicit && !isSuper);
+        boolean coerceType = descriptor.getKind() == ClassKind.INTERFACE || (isExplicit && !isSuper);
         return new ThisOuter(codegen, descriptor, isSuper, coerceType);
     }
 
diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/state/JetTypeMapper.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/state/JetTypeMapper.java
index 835f8b36c8f..99eb010c74c 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/state/JetTypeMapper.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/state/JetTypeMapper.java
@@ -844,7 +844,7 @@ public class JetTypeMapper {
     @NotNull
     private static ClassDescriptor getTraitImplThisParameterClass(@NotNull ClassDescriptor traitDescriptor) {
         for (ClassDescriptor descriptor : DescriptorUtils.getSuperclassDescriptors(traitDescriptor)) {
-            if (descriptor.getKind() != ClassKind.TRAIT) {
+            if (descriptor.getKind() != ClassKind.INTERFACE) {
                 return descriptor;
             }
         }
diff --git a/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/sam/SingleAbstractMethodUtils.java b/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/sam/SingleAbstractMethodUtils.java
index b0049885fcd..92a897733e0 100644
--- a/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/sam/SingleAbstractMethodUtils.java
+++ b/compiler/frontend.java/src/org/jetbrains/kotlin/load/java/sam/SingleAbstractMethodUtils.java
@@ -126,7 +126,7 @@ public class SingleAbstractMethodUtils {
     }
 
     private static boolean isSamInterface(@NotNull ClassDescriptor klass) {
-        if (klass.getKind() != ClassKind.TRAIT) {
+        if (klass.getKind() != ClassKind.INTERFACE) {
             return false;
         }
 
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/descriptors/impl/MutableClassDescriptor.java b/compiler/frontend/src/org/jetbrains/kotlin/descriptors/impl/MutableClassDescriptor.java
index bb75235e71f..9fff1ae4d99 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/descriptors/impl/MutableClassDescriptor.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/descriptors/impl/MutableClassDescriptor.java
@@ -78,7 +78,7 @@ public class MutableClassDescriptor extends ClassDescriptorBase implements Class
         this.scopeForMemberResolution = new WritableScopeImpl(scopeForSupertypeResolution, this, redeclarationHandler, "MemberResolution")
                 .changeLockLevel(WritableScope.LockLevel.BOTH);
 
-        if (kind == ClassKind.TRAIT) {
+        if (kind == ClassKind.INTERFACE) {
             setUpScopeForInitializers(this);
         }
 
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/psi/JetClass.java b/compiler/frontend/src/org/jetbrains/kotlin/psi/JetClass.java
index d804e330851..9faf13b7eb8 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/psi/JetClass.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/psi/JetClass.java
@@ -132,10 +132,10 @@ public class JetClass extends JetTypeParameterListOwnerStub<KotlinClassStub> imp
         return body.getProperties();
     }
 
-    public boolean isTrait() {
+    public boolean isInterface() {
         KotlinClassStub stub = getStub();
         if (stub != null) {
-            return stub.isTrait();
+            return stub.isInterface();
         }
 
         return findChildByType(JetTokens.TRAIT_KEYWORD) != null ||
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/psi/JetPsiUtil.java b/compiler/frontend/src/org/jetbrains/kotlin/psi/JetPsiUtil.java
index a7e62bc18b1..5534a08893e 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/psi/JetPsiUtil.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/psi/JetPsiUtil.java
@@ -427,7 +427,7 @@ public class JetPsiUtil {
     }
 
     public static boolean isTrait(@NotNull JetClassOrObject classOrObject) {
-        return classOrObject instanceof JetClass && ((JetClass) classOrObject).isTrait();
+        return classOrObject instanceof JetClass && ((JetClass) classOrObject).isInterface();
     }
 
     @Nullable
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/psi/psiUtil/jetPsiUtil.kt b/compiler/frontend/src/org/jetbrains/kotlin/psi/psiUtil/jetPsiUtil.kt
index 3537e055824..212c4c150d1 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/psi/psiUtil/jetPsiUtil.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/psi/psiUtil/jetPsiUtil.kt
@@ -116,7 +116,7 @@ public fun JetClassOrObject.effectiveDeclarations(): List<JetDeclaration> =
                 getDeclarations()
         }
 
-public fun JetClass.isAbstract(): Boolean = isTrait() || hasModifier(JetTokens.ABSTRACT_KEYWORD)
+public fun JetClass.isAbstract(): Boolean = isInterface() || hasModifier(JetTokens.ABSTRACT_KEYWORD)
 
 [suppress("UNCHECKED_CAST")]
 public fun <T: PsiElement> PsiElement.replaced(newElement: T): T = replace(newElement) as T
@@ -201,7 +201,7 @@ public fun <T: JetClassOrObject> StubBasedPsiElementBase<out KotlinClassOrObject
 public fun SearchScope.contains(element: PsiElement): Boolean = PsiSearchScopeUtil.isInScope(this, element)
 
 public fun JetClass.isInheritable(): Boolean {
-    return isTrait() || hasModifier(JetTokens.OPEN_KEYWORD) || hasModifier(JetTokens.ABSTRACT_KEYWORD)
+    return isInterface() || hasModifier(JetTokens.OPEN_KEYWORD) || hasModifier(JetTokens.ABSTRACT_KEYWORD)
 }
 
 public fun JetDeclaration.isOverridable(): Boolean {
@@ -213,7 +213,7 @@ public fun JetDeclaration.isOverridable(): Boolean {
 
     if (hasModifier(JetTokens.FINAL_KEYWORD) || hasModifier(JetTokens.PRIVATE_KEYWORD)) return false
 
-    return klass.isTrait() ||
+    return klass.isInterface() ||
         hasModifier(JetTokens.ABSTRACT_KEYWORD) || hasModifier(JetTokens.OPEN_KEYWORD) || hasModifier(JetTokens.OVERRIDE_KEYWORD)
 }
 
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/StubInterfaces.kt b/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/StubInterfaces.kt
index c1036e338bb..a8141b5c78e 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/StubInterfaces.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/StubInterfaces.kt
@@ -42,7 +42,7 @@ public trait KotlinClassOrObjectStub<T : JetClassOrObject> : KotlinStubWithFqNam
 }
 
 public trait KotlinClassStub : KotlinClassOrObjectStub<JetClass> {
-    public fun isTrait(): Boolean
+    public fun isInterface(): Boolean
     public fun isEnumEntry(): Boolean
 }
 
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/elements/JetClassElementType.java b/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/elements/JetClassElementType.java
index 2893b106a96..c59c1311ef2 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/elements/JetClassElementType.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/elements/JetClassElementType.java
@@ -60,7 +60,7 @@ public class JetClassElementType extends JetStubElementType<KotlinClassStub, Jet
         List<String> superNames = PsiUtilPackage.getSuperNames(psi);
         return new KotlinClassStubImpl(
                 getStubType(isEnumEntry), parentStub, StringRef.fromString(fqName != null ? fqName.asString() : null),
-                StringRef.fromString(psi.getName()), Utils.INSTANCE$.wrapStrings(superNames), psi.isTrait(), isEnumEntry,
+                StringRef.fromString(psi.getName()), Utils.INSTANCE$.wrapStrings(superNames), psi.isInterface(), isEnumEntry,
                 psi.isLocal(), psi.isTopLevel());
     }
 
@@ -69,7 +69,7 @@ public class JetClassElementType extends JetStubElementType<KotlinClassStub, Jet
         dataStream.writeName(stub.getName());
         FqName fqName = stub.getFqName();
         dataStream.writeName(fqName == null ? null : fqName.asString());
-        dataStream.writeBoolean(stub.isTrait());
+        dataStream.writeBoolean(stub.isInterface());
         dataStream.writeBoolean(stub.isEnumEntry());
         dataStream.writeBoolean(stub.isLocal());
         dataStream.writeBoolean(stub.isTopLevel());
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinClassStubImpl.kt b/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinClassStubImpl.kt
index 1e6cfaf220d..f062e9092b1 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinClassStubImpl.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/psi/stubs/impl/KotlinClassStubImpl.kt
@@ -46,7 +46,7 @@ public class KotlinClassStubImpl(
         return FqName(stringRef)
     }
 
-    override fun isTrait() = isTrait
+    override fun isInterface() = isTrait
     override fun isEnumEntry() = isEnumEntry
     override fun isLocal() = isLocal
     override fun getName() = StringRef.toString(name)
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java
index 0a21817480c..a2502006e9d 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java
@@ -290,7 +290,7 @@ public class BodyResolver {
 
             @Override
             public void visitDelegationByExpressionSpecifier(@NotNull JetDelegatorByExpressionSpecifier specifier) {
-                if (descriptor.getKind() == ClassKind.TRAIT) {
+                if (descriptor.getKind() == ClassKind.INTERFACE) {
                     trace.report(DELEGATION_IN_TRAIT.on(specifier));
                 }
                 JetType supertype = trace.getBindingContext().get(BindingContext.TYPE, specifier.getTypeReference());
@@ -299,7 +299,7 @@ public class BodyResolver {
                     DeclarationDescriptor declarationDescriptor = supertype.getConstructor().getDeclarationDescriptor();
                     if (declarationDescriptor instanceof ClassDescriptor) {
                         ClassDescriptor classDescriptor = (ClassDescriptor) declarationDescriptor;
-                        if (classDescriptor.getKind() != ClassKind.TRAIT) {
+                        if (classDescriptor.getKind() != ClassKind.INTERFACE) {
                             trace.report(DELEGATION_NOT_TO_TRAIT.on(specifier.getTypeReference()));
                         }
                     }
@@ -319,13 +319,13 @@ public class BodyResolver {
             public void visitDelegationToSuperCallSpecifier(@NotNull JetDelegatorToSuperCall call) {
                 JetValueArgumentList valueArgumentList = call.getValueArgumentList();
                 PsiElement elementToMark = valueArgumentList == null ? call : valueArgumentList;
-                if (descriptor.getKind() == ClassKind.TRAIT) {
+                if (descriptor.getKind() == ClassKind.INTERFACE) {
                     trace.report(SUPERTYPE_INITIALIZED_IN_TRAIT.on(elementToMark));
                 }
                 JetTypeReference typeReference = call.getTypeReference();
                 if (typeReference == null) return;
                 if (primaryConstructor == null) {
-                    if (descriptor.getKind() != ClassKind.TRAIT) {
+                    if (descriptor.getKind() != ClassKind.INTERFACE) {
                         trace.report(SUPERTYPE_INITIALIZED_WITHOUT_PRIMARY_CONSTRUCTOR.on(call));
                     }
                     recordSupertype(typeReference, trace.getBindingContext().get(BindingContext.TYPE, typeReference));
@@ -339,7 +339,7 @@ public class BodyResolver {
                     recordSupertype(typeReference, supertype);
                     ClassDescriptor classDescriptor = TypeUtils.getClassDescriptor(supertype);
                     if (classDescriptor != null) {
-                        if (classDescriptor.getKind() == ClassKind.TRAIT) {
+                        if (classDescriptor.getKind() == ClassKind.INTERFACE) {
                             trace.report(CONSTRUCTOR_IN_TRAIT.on(elementToMark));
                         }
                         // allow only one delegating constructor
@@ -368,7 +368,7 @@ public class BodyResolver {
                     // A "singleton in supertype" diagnostic will be reported later
                     return;
                 }
-                if (descriptor.getKind() != ClassKind.TRAIT &&
+                if (descriptor.getKind() != ClassKind.INTERFACE &&
                     descriptor.getUnsubstitutedPrimaryConstructor() != null &&
                     !superClass.getConstructors().isEmpty() &&
                     !ErrorUtils.isError(superClass)
@@ -425,11 +425,11 @@ public class BodyResolver {
 
             ClassDescriptor classDescriptor = TypeUtils.getClassDescriptor(supertype);
             if (classDescriptor != null) {
-                if (classDescriptor.getKind() != ClassKind.TRAIT) {
+                if (classDescriptor.getKind() != ClassKind.INTERFACE) {
                     if (supertypeOwner.getKind() == ClassKind.ENUM_CLASS) {
                         trace.report(CLASS_IN_SUPERTYPE_FOR_ENUM.on(typeReference));
                     }
-                    else if (supertypeOwner.getKind() == ClassKind.TRAIT &&
+                    else if (supertypeOwner.getKind() == ClassKind.INTERFACE &&
                              !classAppeared && !TypesPackage.isDynamic(supertype) /* avoid duplicate diagnostics */) {
                         trace.report(TRAIT_WITH_SUPERCLASS.on(typeReference));
                     }
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.java
index 3b2eb7b003b..393937ff7dc 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.java
@@ -241,7 +241,7 @@ public class DeclarationsChecker {
         checkPrimaryConstructor(aClass, classDescriptor);
         checkTypeParameters(aClass);
 
-        if (aClass.isTrait()) {
+        if (aClass.isInterface()) {
             checkTraitModifiers(aClass);
             checkConstructorInTrait(aClass);
         }
@@ -380,7 +380,7 @@ public class DeclarationsChecker {
                 trace.report(ABSTRACT_PROPERTY_IN_NON_ABSTRACT_CLASS.on(property, name != null ? name : "", classDescriptor));
                 return;
             }
-            if (classDescriptor.getKind() == ClassKind.TRAIT) {
+            if (classDescriptor.getKind() == ClassKind.INTERFACE) {
                 trace.report(ABSTRACT_MODIFIER_IN_TRAIT.on(property));
             }
         }
@@ -416,7 +416,7 @@ public class DeclarationsChecker {
             return;
         }
         DeclarationDescriptor containingDeclaration = propertyDescriptor.getContainingDeclaration();
-        boolean inTrait = containingDeclaration instanceof ClassDescriptor && ((ClassDescriptor)containingDeclaration).getKind() == ClassKind.TRAIT;
+        boolean inTrait = containingDeclaration instanceof ClassDescriptor && ((ClassDescriptor)containingDeclaration).getKind() == ClassKind.INTERFACE;
         JetExpression initializer = property.getInitializer();
         JetPropertyDelegate delegate = property.getDelegate();
         boolean backingFieldRequired =
@@ -473,7 +473,7 @@ public class DeclarationsChecker {
         checkDeclaredTypeInPublicMember(function, functionDescriptor);
         if (containingDescriptor instanceof ClassDescriptor) {
             ClassDescriptor classDescriptor = (ClassDescriptor) containingDescriptor;
-            boolean inTrait = classDescriptor.getKind() == ClassKind.TRAIT;
+            boolean inTrait = classDescriptor.getKind() == ClassKind.INTERFACE;
             if (hasAbstractModifier && !classCanHaveAbstractMembers(classDescriptor)) {
                 trace.report(ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS.on(function, functionDescriptor.getName().asString(), classDescriptor));
             }
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DelegationResolver.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DelegationResolver.java
index 6fce249ac25..2a832d42751 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DelegationResolver.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DelegationResolver.java
@@ -196,7 +196,7 @@ public final class DelegationResolver<T extends CallableMemberDescriptor> {
     private static boolean isNotTrait(@Nullable DeclarationDescriptor descriptor) {
         if (descriptor instanceof ClassDescriptor) {
             ClassKind kind = ((ClassDescriptor) descriptor).getKind();
-            return kind != ClassKind.TRAIT;
+            return kind != ClassKind.INTERFACE;
         }
         return false;
     }
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java
index 80cb218b4b6..726dd77c7c3 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java
@@ -148,7 +148,7 @@ public class DescriptorResolver {
     private boolean containsClass(Collection<JetType> result) {
         for (JetType type : result) {
             ClassifierDescriptor descriptor = type.getConstructor().getDeclarationDescriptor();
-            if (descriptor instanceof ClassDescriptor && ((ClassDescriptor) descriptor).getKind() != ClassKind.TRAIT) {
+            if (descriptor instanceof ClassDescriptor && ((ClassDescriptor) descriptor).getKind() != ClassKind.INTERFACE) {
                 return true;
             }
         }
@@ -331,7 +331,7 @@ public class DescriptorResolver {
     public static Modality getDefaultModality(DeclarationDescriptor containingDescriptor, Visibility visibility, boolean isBodyPresent) {
         Modality defaultModality;
         if (containingDescriptor instanceof ClassDescriptor) {
-            boolean isTrait = ((ClassDescriptor) containingDescriptor).getKind() == ClassKind.TRAIT;
+            boolean isTrait = ((ClassDescriptor) containingDescriptor).getKind() == ClassKind.INTERFACE;
             boolean isDefinitelyAbstract = isTrait && !isBodyPresent;
             Modality basicModality = isTrait && !Visibilities.isPrivate(visibility) ? Modality.OPEN : Modality.FINAL;
             defaultModality = isDefinitelyAbstract ? Modality.ABSTRACT : basicModality;
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/LazyTopDownAnalyzer.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/LazyTopDownAnalyzer.java
index e50fd874135..5d2b05c58a8 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/LazyTopDownAnalyzer.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/LazyTopDownAnalyzer.java
@@ -204,7 +204,7 @@ public class LazyTopDownAnalyzer {
                                     if (DescriptorUtils.isSingletonOrAnonymousObject(classDescriptor)) {
                                         trace.report(SECONDARY_CONSTRUCTOR_IN_OBJECT.on((JetSecondaryConstructor) jetDeclaration));
                                     }
-                                    else if (classDescriptor.getKind() == ClassKind.TRAIT) {
+                                    else if (classDescriptor.getKind() == ClassKind.INTERFACE) {
                                         trace.report(CONSTRUCTOR_IN_TRAIT.on(jetDeclaration));
                                     }
                                 }
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/data/JetClassInfo.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/data/JetClassInfo.java
index ff3a7317a56..e907956aeeb 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/data/JetClassInfo.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/data/JetClassInfo.java
@@ -31,8 +31,8 @@ public class JetClassInfo extends JetClassOrObjectInfo<JetClass> {
         if (element instanceof JetEnumEntry) {
             this.kind = ClassKind.ENUM_ENTRY;
         }
-        else if (element.isTrait()) {
-            this.kind = ClassKind.TRAIT;
+        else if (element.isInterface()) {
+            this.kind = ClassKind.INTERFACE;
         }
         else if (element.isAnnotation()) {
             this.kind = ClassKind.ANNOTATION_CLASS;
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassDescriptor.java b/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassDescriptor.java
index 6635a911515..6756f3a14fd 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassDescriptor.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyClassDescriptor.java
@@ -128,7 +128,7 @@ public class LazyClassDescriptor extends ClassDescriptorBase implements ClassDes
             this.modality = Modality.FINAL;
         }
         else {
-            Modality defaultModality = kind == ClassKind.TRAIT ? Modality.ABSTRACT : Modality.FINAL;
+            Modality defaultModality = kind == ClassKind.INTERFACE ? Modality.ABSTRACT : Modality.FINAL;
             this.modality = resolveModalityFromModifiers(modifierList, defaultModality);
         }
 
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/types/CastDiagnosticsUtil.java b/compiler/frontend/src/org/jetbrains/kotlin/types/CastDiagnosticsUtil.java
index 8942159e9c9..118e38ecd50 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/types/CastDiagnosticsUtil.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/types/CastDiagnosticsUtil.java
@@ -103,7 +103,7 @@ public class CastDiagnosticsUtil {
 
     private static boolean isTrait(@NotNull JetType type) {
         ClassifierDescriptor descriptor = type.getConstructor().getDeclarationDescriptor();
-        return descriptor instanceof ClassDescriptor && ((ClassDescriptor) descriptor).getKind() == ClassKind.TRAIT;
+        return descriptor instanceof ClassDescriptor && ((ClassDescriptor) descriptor).getKind() == ClassKind.INTERFACE;
     }
 
     /**
diff --git a/compiler/light-classes/src/org/jetbrains/kotlin/asJava/KotlinLightClassForExplicitDeclaration.java b/compiler/light-classes/src/org/jetbrains/kotlin/asJava/KotlinLightClassForExplicitDeclaration.java
index 574be83018a..a4b53376456 100644
--- a/compiler/light-classes/src/org/jetbrains/kotlin/asJava/KotlinLightClassForExplicitDeclaration.java
+++ b/compiler/light-classes/src/org/jetbrains/kotlin/asJava/KotlinLightClassForExplicitDeclaration.java
@@ -25,7 +25,6 @@ import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.*;
 import com.intellij.psi.PsiPackage;
-import com.intellij.psi.impl.PsiManagerImpl;
 import com.intellij.psi.impl.compiled.ClsFileImpl;
 import com.intellij.psi.impl.java.stubs.PsiJavaFileStub;
 import com.intellij.psi.impl.light.LightClass;
@@ -500,7 +499,7 @@ public class KotlinLightClassForExplicitDeclaration extends KotlinWrappingLightC
     public boolean isInterface() {
         if (!(classOrObject instanceof JetClass)) return false;
         JetClass jetClass = (JetClass) classOrObject;
-        return jetClass.isTrait() || jetClass.isAnnotation();
+        return jetClass.isInterface() || jetClass.isAnnotation();
     }
 
     @Override
diff --git a/compiler/tests/org/jetbrains/kotlin/test/util/DescriptorValidator.java b/compiler/tests/org/jetbrains/kotlin/test/util/DescriptorValidator.java
index 73c63c984ff..33c4e68ffad 100644
--- a/compiler/tests/org/jetbrains/kotlin/test/util/DescriptorValidator.java
+++ b/compiler/tests/org/jetbrains/kotlin/test/util/DescriptorValidator.java
@@ -235,7 +235,7 @@ public class DescriptorValidator {
             validateTypeParameters(collector, descriptor.getTypeConstructor().getParameters());
 
             Collection<JetType> supertypes = descriptor.getTypeConstructor().getSupertypes();
-            if (supertypes.isEmpty() && descriptor.getKind() != ClassKind.TRAIT
+            if (supertypes.isEmpty() && descriptor.getKind() != ClassKind.INTERFACE
                 && !KotlinBuiltIns.isSpecialClassWithNoSupertypes(descriptor)) {
                 report(collector, descriptor, "No supertypes for non-trait");
             }
diff --git a/compiler/tests/org/jetbrains/kotlin/types/JetDefaultModalityModifiersTest.java b/compiler/tests/org/jetbrains/kotlin/types/JetDefaultModalityModifiersTest.java
index d1ef7b9d10e..4a060ba3953 100644
--- a/compiler/tests/org/jetbrains/kotlin/types/JetDefaultModalityModifiersTest.java
+++ b/compiler/tests/org/jetbrains/kotlin/types/JetDefaultModalityModifiersTest.java
@@ -171,7 +171,7 @@ public class JetDefaultModalityModifiersTest extends JetLiteFixture {
         }
 
         public void testTraitModality(String classDeclaration, Modality expectedModality) {
-            testClassModality(classDeclaration, ClassKind.TRAIT, expectedModality);
+            testClassModality(classDeclaration, ClassKind.INTERFACE, expectedModality);
         }
 
         public void testEnumModality(String classDeclaration, Modality expectedModality) {
@@ -187,7 +187,7 @@ public class JetDefaultModalityModifiersTest extends JetLiteFixture {
         }
 
         public void testFunctionModalityInTrait(String classWithFunction, Modality expectedModality) {
-            testFunctionModality(classWithFunction, ClassKind.TRAIT, expectedModality);
+            testFunctionModality(classWithFunction, ClassKind.INTERFACE, expectedModality);
         }
 
         public void testPropertyModalityInClass(String classWithProperty, Modality expectedModality) {
@@ -199,7 +199,7 @@ public class JetDefaultModalityModifiersTest extends JetLiteFixture {
         }
 
         public void testPropertyModalityInTrait(String classWithProperty, Modality expectedModality) {
-            testPropertyModality(classWithProperty, ClassKind.TRAIT, expectedModality);
+            testPropertyModality(classWithProperty, ClassKind.INTERFACE, expectedModality);
         }
 
         public void testPropertyAccessorModalityInClass(String classWithPropertyWithAccessor, Modality expectedModality) {
@@ -207,7 +207,7 @@ public class JetDefaultModalityModifiersTest extends JetLiteFixture {
         }
 
         public void testPropertyAccessorModalityInTrait(String classWithPropertyWithAccessor, Modality expectedModality) {
-            testPropertyAccessorModality(classWithPropertyWithAccessor, ClassKind.TRAIT, expectedModality, true);
+            testPropertyAccessorModality(classWithPropertyWithAccessor, ClassKind.INTERFACE, expectedModality, true);
         }
 
         public void testPropertyAccessorModalityInClass(String classWithPropertyWithAccessor, Modality expectedModality, boolean isGetter) {
@@ -215,7 +215,7 @@ public class JetDefaultModalityModifiersTest extends JetLiteFixture {
         }
 
         public void testPropertyAccessorModalityInTrait(String classWithPropertyWithAccessor, Modality expectedModality, boolean isGetter) {
-            testPropertyAccessorModality(classWithPropertyWithAccessor, ClassKind.TRAIT, expectedModality, isGetter);
+            testPropertyAccessorModality(classWithPropertyWithAccessor, ClassKind.INTERFACE, expectedModality, isGetter);
         }
     }
 
diff --git a/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaClassDescriptor.kt b/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaClassDescriptor.kt
index 193ca90b999..3005f1a847b 100644
--- a/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaClassDescriptor.kt
+++ b/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaClassDescriptor.kt
@@ -54,7 +54,7 @@ class LazyJavaClassDescriptor(
 
     private val kind = when {
         jClass.isAnnotationType() -> ClassKind.ANNOTATION_CLASS
-        jClass.isInterface() -> ClassKind.TRAIT
+        jClass.isInterface() -> ClassKind.INTERFACE
         jClass.isEnum() -> ClassKind.ENUM_CLASS
         else -> ClassKind.CLASS
     }
diff --git a/core/descriptors/src/org/jetbrains/kotlin/descriptors/ClassKind.java b/core/descriptors/src/org/jetbrains/kotlin/descriptors/ClassKind.java
index 6d2864ded86..4566e98a962 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/descriptors/ClassKind.java
+++ b/core/descriptors/src/org/jetbrains/kotlin/descriptors/ClassKind.java
@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.descriptors;
 
 public enum ClassKind {
     CLASS,
-    TRAIT,
+    INTERFACE,
     ENUM_CLASS,
     ENUM_ENTRY,
     ANNOTATION_CLASS,
diff --git a/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.java b/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.java
index 275bd81f010..edd6e263dea 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.java
+++ b/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.java
@@ -988,7 +988,7 @@ public class DescriptorRendererImpl implements DescriptorRenderer {
         if (!startFromName) {
             renderAnnotations(klass, builder);
             renderVisibility(klass.getVisibility(), builder);
-            if (!(klass.getKind() == ClassKind.TRAIT && klass.getModality() == Modality.ABSTRACT
+            if (!(klass.getKind() == ClassKind.INTERFACE && klass.getModality() == Modality.ABSTRACT
                 || klass.getKind().isSingleton() && klass.getModality() == Modality.FINAL)) {
                 renderModality(klass.getModality(), builder);
             }
@@ -1056,7 +1056,7 @@ public class DescriptorRendererImpl implements DescriptorRenderer {
         switch (klass.getKind()) {
             case CLASS:
                 return "class";
-            case TRAIT:
+            case INTERFACE:
                 return "trait";
             case ENUM_CLASS:
                 return "enum class";
diff --git a/core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorUtils.java b/core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorUtils.java
index 1714a62f5e4..c47f4438131 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorUtils.java
+++ b/core/descriptors/src/org/jetbrains/kotlin/resolve/DescriptorUtils.java
@@ -303,7 +303,7 @@ public class DescriptorUtils {
     }
 
     public static boolean isTrait(@Nullable DeclarationDescriptor descriptor) {
-        return isKindOf(descriptor, ClassKind.TRAIT);
+        return isKindOf(descriptor, ClassKind.INTERFACE);
     }
 
     public static boolean isClass(@Nullable DeclarationDescriptor descriptor) {
@@ -332,7 +332,7 @@ public class DescriptorUtils {
         Collection<JetType> superclassTypes = classDescriptor.getTypeConstructor().getSupertypes();
         for (JetType type : superclassTypes) {
             ClassDescriptor superClassDescriptor = getClassDescriptorForType(type);
-            if (superClassDescriptor.getKind() != ClassKind.TRAIT) {
+            if (superClassDescriptor.getKind() != ClassKind.INTERFACE) {
                 return type;
             }
         }
@@ -361,7 +361,7 @@ public class DescriptorUtils {
         if (isAnonymousObject(classDescriptor)) {
             return Visibilities.INTERNAL;
         }
-        assert classKind == ClassKind.CLASS || classKind == ClassKind.TRAIT || classKind == ClassKind.ANNOTATION_CLASS;
+        assert classKind == ClassKind.CLASS || classKind == ClassKind.INTERFACE || classKind == ClassKind.ANNOTATION_CLASS;
         return Visibilities.PUBLIC;
     }
 
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java b/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java
index eabf52491cc..e5d13c2f064 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java
@@ -90,7 +90,7 @@ public class Flags {
         switch (kind) {
             case CLASS:
                 return ProtoBuf.Class.Kind.CLASS;
-            case TRAIT:
+            case INTERFACE:
                 return ProtoBuf.Class.Kind.TRAIT;
             case ENUM_CLASS:
                 return ProtoBuf.Class.Kind.ENUM_CLASS;
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt
index 5187e317200..3eedccd2fa3 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt
@@ -48,7 +48,7 @@ fun visibility(visibility: ProtoBuf.Visibility) = when (visibility) {
 
 public fun classKind(kind: ProtoBuf.Class.Kind): ClassKind = when (kind) {
     ProtoBuf.Class.Kind.CLASS -> ClassKind.CLASS
-    ProtoBuf.Class.Kind.TRAIT -> ClassKind.TRAIT
+    ProtoBuf.Class.Kind.TRAIT -> ClassKind.INTERFACE
     ProtoBuf.Class.Kind.ENUM_CLASS -> ClassKind.ENUM_CLASS
     ProtoBuf.Class.Kind.ENUM_ENTRY -> ClassKind.ENUM_ENTRY
     ProtoBuf.Class.Kind.ANNOTATION_CLASS -> ClassKind.ANNOTATION_CLASS
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetDescriptorIconProvider.java b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetDescriptorIconProvider.java
index 5a366084b13..d1399209d39 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetDescriptorIconProvider.java
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetDescriptorIconProvider.java
@@ -101,7 +101,7 @@ public final class JetDescriptorIconProvider {
         }
         if (descriptor instanceof ClassDescriptor) {
             switch (((ClassDescriptor) descriptor).getKind()) {
-                case TRAIT:
+                case INTERFACE:
                     return JetIcons.TRAIT;
                 case ENUM_CLASS:
                     return JetIcons.ENUM;
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetIconProvider.java b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetIconProvider.java
index fbc62878207..34ccea8e388 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetIconProvider.java
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/JetIconProvider.java
@@ -142,7 +142,7 @@ public class JetIconProvider extends IconProvider implements DumbAware {
 
         if (psiElement instanceof JetClass) {
             JetClass jetClass = (JetClass) psiElement;
-            if (jetClass.isTrait()) {
+            if (jetClass.isInterface()) {
                 return JetIcons.TRAIT;
             }
 
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/KotlinSuppressableWarningProblemGroup.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/KotlinSuppressableWarningProblemGroup.kt
index 7212b49c771..a53cb5ffbd0 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/KotlinSuppressableWarningProblemGroup.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/KotlinSuppressableWarningProblemGroup.kt
@@ -83,7 +83,7 @@ private object DeclarationKindDetector : JetVisitor<AnnotationHostKind?, Unit?>(
 
     override fun visitDeclaration(d: JetDeclaration, _: Unit?) = null
 
-    override fun visitClass(d: JetClass, _: Unit?) = detect(d, if (d.isTrait()) "trait" else "class")
+    override fun visitClass(d: JetClass, _: Unit?) = detect(d, if (d.isInterface()) "trait" else "class")
 
     override fun visitNamedFunction(d: JetNamedFunction, _: Unit?) = detect(d, "fun")
 
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/TypeKindHighlightingVisitor.java b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/TypeKindHighlightingVisitor.java
index 5d26c4903ca..a20e6cb0b9a 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/TypeKindHighlightingVisitor.java
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/highlighter/TypeKindHighlightingVisitor.java
@@ -93,7 +93,7 @@ class TypeKindHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
     @NotNull
     private static TextAttributesKey textAttributesKeyForClass(@NotNull ClassDescriptor descriptor) {
         switch (descriptor.getKind()) {
-            case TRAIT:
+            case INTERFACE:
                 return JetHighlightingColors.TRAIT;
             case ANNOTATION_CLASS:
                 return JetHighlightingColors.ANNOTATION;
diff --git a/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/AllClassesCompletion.kt b/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/AllClassesCompletion.kt
index 6072e8ad42f..862421634f5 100644
--- a/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/AllClassesCompletion.kt
+++ b/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/AllClassesCompletion.kt
@@ -82,7 +82,7 @@ class AllClassesCompletion(val parameters: CompletionParameters,
             if (psiClass!! !is KotlinLightClass) { // Kotlin class should have already been added as kotlin element before
                 val kind = when {
                     psiClass.isAnnotationType() -> ClassKind.ANNOTATION_CLASS
-                    psiClass.isInterface() -> ClassKind.TRAIT
+                    psiClass.isInterface() -> ClassKind.INTERFACE
                     psiClass.isEnum() -> ClassKind.ENUM_CLASS
                     else -> ClassKind.CLASS
                 }
diff --git a/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/TypeInstantiationItems.kt b/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/TypeInstantiationItems.kt
index 630cb57ad0a..249f64b4dcc 100644
--- a/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/TypeInstantiationItems.kt
+++ b/idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/TypeInstantiationItems.kt
@@ -153,7 +153,7 @@ class TypeInstantiationItems(
         val insertHandler: InsertHandler<LookupElement>
         val typeText = IdeDescriptorRenderers.SOURCE_CODE.renderClassifierName(classifier) + IdeDescriptorRenderers.SOURCE_CODE.renderTypeArguments(typeArgsToUse)
         if (isAbstract) {
-            val constructorParenthesis = if (classifier.getKind() != ClassKind.TRAIT) "()" else ""
+            val constructorParenthesis = if (classifier.getKind() != ClassKind.INTERFACE) "()" else ""
             itemText += constructorParenthesis
             itemText = "object: " + itemText + "{...}"
             lookupString = "object"
@@ -242,7 +242,7 @@ class TypeInstantiationItems(
     }
 
     private fun addSamConstructorItem(collection: MutableCollection<LookupElement>, `class`: ClassDescriptor, tail: Tail?) {
-        if (`class`.getKind() == ClassKind.TRAIT) {
+        if (`class`.getKind() == ClassKind.INTERFACE) {
             val container = `class`.getContainingDeclaration()
             val scope = when (container) {
                 is PackageFragmentDescriptor -> container.getMemberScope()
diff --git a/idea/src/org/jetbrains/kotlin/idea/actions/JetAddFunctionToClassifierAction.java b/idea/src/org/jetbrains/kotlin/idea/actions/JetAddFunctionToClassifierAction.java
index d581cd23e22..b26c66c04a8 100644
--- a/idea/src/org/jetbrains/kotlin/idea/actions/JetAddFunctionToClassifierAction.java
+++ b/idea/src/org/jetbrains/kotlin/idea/actions/JetAddFunctionToClassifierAction.java
@@ -94,7 +94,7 @@ public class JetAddFunctionToClassifierAction implements QuestionAction {
                         }
 
                         String functionBody = "";
-                        if (typeDescriptor.getKind() != ClassKind.TRAIT && functionDescriptor.getModality() != Modality.ABSTRACT) {
+                        if (typeDescriptor.getKind() != ClassKind.INTERFACE && functionDescriptor.getModality() != Modality.ABSTRACT) {
                             functionBody = "{}";
                             JetType returnType = functionDescriptor.getReturnType();
                             if (returnType == null || !KotlinBuiltIns.isUnit(returnType)) {
diff --git a/idea/src/org/jetbrains/kotlin/idea/debugger/JetPositionManager.kt b/idea/src/org/jetbrains/kotlin/idea/debugger/JetPositionManager.kt
index aadb2fc84db..17077eaf2a2 100644
--- a/idea/src/org/jetbrains/kotlin/idea/debugger/JetPositionManager.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/debugger/JetPositionManager.kt
@@ -371,7 +371,7 @@ public class JetPositionManager(private val myDebugProcess: DebugProcess) : Mult
                 return null
             }
 
-            if (jetClass is JetClass && jetClass.isTrait()) {
+            if (jetClass is JetClass && jetClass.isInterface()) {
                 return typeMapper.mapTraitImpl(classDescriptor).getInternalName()
             }
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/findUsages/JetElementDescriptionProvider.kt b/idea/src/org/jetbrains/kotlin/idea/findUsages/JetElementDescriptionProvider.kt
index cd779fdc29b..5df9b4e6357 100644
--- a/idea/src/org/jetbrains/kotlin/idea/findUsages/JetElementDescriptionProvider.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/findUsages/JetElementDescriptionProvider.kt
@@ -36,7 +36,7 @@ public class JetElementDescriptionProvider : ElementDescriptionProvider {
         val targetElement = element.unwrapped
 
         fun elementKind() = when (targetElement) {
-            is JetClass -> if (targetElement.isTrait()) "trait" else "class"
+            is JetClass -> if (targetElement.isInterface()) "trait" else "class"
             is JetObjectDeclaration -> "object"
             is JetNamedFunction -> "function"
             is JetSecondaryConstructor -> "constructor"
diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt
index ff63a521f6b..df30887b629 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt
@@ -136,7 +136,7 @@ private fun collectSuperDeclarationMarkers(declaration: JetDeclaration, result:
 }
 
 private fun collectInheritedClassMarker(element: JetClass, result: MutableCollection<LineMarkerInfo<*>>) {
-    val isTrait = element.isTrait()
+    val isTrait = element.isInterface()
     if (!(isTrait || element.hasModifier(JetTokens.OPEN_KEYWORD) || element.hasModifier(JetTokens.ABSTRACT_KEYWORD))) {
         return
     }
diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenPropertyMarker.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenPropertyMarker.kt
index a075fbb79f9..9ae4c4a1353 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenPropertyMarker.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenPropertyMarker.kt
@@ -123,6 +123,6 @@ public fun isImplemented(declaration: JetNamedDeclaration): Boolean {
 
     if (parent !is JetClass) return false
 
-    return (parent as JetClass).isTrait() && (declaration !is JetDeclarationWithBody || !declaration.hasBody()) && (declaration !is JetWithExpressionInitializer || !declaration.hasInitializer())
+    return (parent as JetClass).isInterface() && (declaration !is JetDeclarationWithBody || !declaration.hasBody()) && (declaration !is JetWithExpressionInitializer || !declaration.hasInitializer())
 }
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/liveTemplates/macro/JetAnonymousSuperMacro.java b/idea/src/org/jetbrains/kotlin/idea/liveTemplates/macro/JetAnonymousSuperMacro.java
index 27f6d7c5aa1..35442e0f725 100644
--- a/idea/src/org/jetbrains/kotlin/idea/liveTemplates/macro/JetAnonymousSuperMacro.java
+++ b/idea/src/org/jetbrains/kotlin/idea/liveTemplates/macro/JetAnonymousSuperMacro.java
@@ -103,7 +103,7 @@ public class JetAnonymousSuperMacro extends Macro {
             ClassDescriptor classDescriptor = (ClassDescriptor) descriptor;
             if (!classDescriptor.getModality().isOverridable()) continue;
             ClassKind kind = classDescriptor.getKind();
-            if (kind == ClassKind.TRAIT || kind == ClassKind.CLASS) {
+            if (kind == ClassKind.INTERFACE || kind == ClassKind.CLASS) {
                 PsiElement declaration = DescriptorToSourceUtils.descriptorToDeclaration(descriptor);
                 if (declaration != null) {
                     result.add((PsiNamedElement) declaration);
diff --git a/idea/src/org/jetbrains/kotlin/idea/quickfix/AddFunctionToSupertypeFix.java b/idea/src/org/jetbrains/kotlin/idea/quickfix/AddFunctionToSupertypeFix.java
index 2d3112eaa28..ea5a20a9379 100644
--- a/idea/src/org/jetbrains/kotlin/idea/quickfix/AddFunctionToSupertypeFix.java
+++ b/idea/src/org/jetbrains/kotlin/idea/quickfix/AddFunctionToSupertypeFix.java
@@ -97,7 +97,7 @@ public class AddFunctionToSupertypeFix extends JetHintAction<JetNamedFunction> {
     ) {
         // TODO: support for generics.
         Modality modality = typeDescriptor.getModality();
-        if (typeDescriptor.getKind() == ClassKind.TRAIT) {
+        if (typeDescriptor.getKind() == ClassKind.INTERFACE) {
             modality = Modality.OPEN;
         }
         return functionDescriptor.copy(
diff --git a/idea/src/org/jetbrains/kotlin/idea/quickfix/AddOpenModifierToClassDeclarationFix.java b/idea/src/org/jetbrains/kotlin/idea/quickfix/AddOpenModifierToClassDeclarationFix.java
index 62fa3494005..6b84f3b8811 100644
--- a/idea/src/org/jetbrains/kotlin/idea/quickfix/AddOpenModifierToClassDeclarationFix.java
+++ b/idea/src/org/jetbrains/kotlin/idea/quickfix/AddOpenModifierToClassDeclarationFix.java
@@ -58,7 +58,7 @@ public class AddOpenModifierToClassDeclarationFix extends JetIntentionAction<Jet
             }
             if (target instanceof JetClass && QuickFixUtil.canModifyElement(target)) {
                 classDeclaration = (JetClass) target;
-                return !(classDeclaration.isEnum() || classDeclaration.isTrait());
+                return !(classDeclaration.isEnum() || classDeclaration.isInterface());
             }
         }
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/CallableBuilder.kt b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/CallableBuilder.kt
index 397ab2e0a4e..fada60b517c 100644
--- a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/CallableBuilder.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/CallableBuilder.kt
@@ -452,7 +452,7 @@ class CallableBuilder(val config: CallableBuilderConfiguration) {
                 val declaration : JetNamedDeclaration = when (callableInfo.kind) {
                     CallableKind.FUNCTION, CallableKind.SECONDARY_CONSTRUCTOR -> {
                         val body = when {
-                            containingElement is JetClass && containingElement.isTrait() && !config.isExtension -> ""
+                            containingElement is JetClass && containingElement.isInterface() && !config.isExtension -> ""
                             else -> "{}"
                         }
                         if (callableInfo.kind == CallableKind.FUNCTION) {
diff --git a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/templateExpressions.kt b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/templateExpressions.kt
index fa1b9b464e0..1256b9ac617 100644
--- a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/templateExpressions.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/templateExpressions.kt
@@ -111,7 +111,7 @@ private abstract class TypeExpression(public val typeCandidates: List<TypeCandid
         override val cachedLookupElements: Array<LookupElement> =
                 typeCandidates.map {
                     val descriptor = it.theType.getConstructor().getDeclarationDescriptor() as ClassDescriptor
-                    val text = it.renderedType!! + if (descriptor.getKind() == ClassKind.TRAIT) "" else "()"
+                    val text = it.renderedType!! + if (descriptor.getKind() == ClassKind.INTERFACE) "" else "()"
                     LookupElementBuilder.create(it, text)
                 }.copyToArray()
     }
diff --git a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createClass/createClassUtils.kt b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createClass/createClassUtils.kt
index 569a625c1eb..239d37f140e 100644
--- a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createClass/createClassUtils.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createClass/createClassUtils.kt
@@ -107,7 +107,7 @@ private fun JetExpression.getInheritableTypeInfo(
         when (classKind) {
             ClassKind.ENUM_ENTRY -> isEnum && containingDeclaration == DescriptorToSourceUtils.descriptorToDeclaration(descriptor)
             ClassKind.TRAIT -> containingDeclaration !is PsiClass
-                               || (descriptor as? ClassDescriptor)?.getKind() == ClassDescriptorKind.TRAIT
+                               || (descriptor as? ClassDescriptor)?.getKind() == ClassDescriptorKind.INTERFACE
             else -> canHaveSubtypes
         }
     }
diff --git a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createVariable/CreateParameterActionFactory.kt b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createVariable/CreateParameterActionFactory.kt
index 5942ceafd9a..ca2b5b3a18c 100644
--- a/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createVariable/CreateParameterActionFactory.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/createVariable/CreateParameterActionFactory.kt
@@ -92,13 +92,13 @@ object CreateParameterActionFactory: JetSingleIntentionActionFactory() {
                         it is JetClassInitializer -> it.getParent()?.getParent() as? JetClass
                         it is JetDelegationSpecifier -> {
                             val klass = it.getStrictParentOfType<JetClass>()
-                            if (klass != null && !klass.isTrait() && klass !is JetEnumEntry) klass else null
+                            if (klass != null && !klass.isInterface() && klass !is JetEnumEntry) klass else null
                         }
                         it is JetClassBody -> {
                             val klass = it.getParent() as? JetClass
                             when {
                                 klass is JetEnumEntry -> chooseContainingClass(klass)
-                                klass != null && klass.isTrait() -> null
+                                klass != null && klass.isInterface() -> null
                                 else -> klass
                             }
                         }
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignature.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignature.kt
index f37b1c7bfd5..bca150a16c8 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignature.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignature.kt
@@ -119,7 +119,7 @@ public class JetChangeSignature(project: Project,
     private fun preferContainedInClass(descriptorsForSignatureChange: Collection<FunctionDescriptor>): FunctionDescriptor {
         for (descriptor in descriptorsForSignatureChange) {
             val containingDeclaration = descriptor.getContainingDeclaration()
-            if (containingDeclaration is ClassDescriptor && containingDeclaration.getKind() != ClassKind.TRAIT) {
+            if (containingDeclaration is ClassDescriptor && containingDeclaration.getKind() != ClassKind.INTERFACE) {
                 return descriptor
             }
         }
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignatureData.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignatureData.kt
index d93079dd8e4..6bfcec29640 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignatureData.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/JetChangeSignatureData.kt
@@ -145,7 +145,7 @@ public class JetChangeSignatureData(
     override fun canChangeVisibility(): Boolean {
         if (DescriptorUtils.isLocal(baseDescriptor)) return false;
         val parent = baseDescriptor.getContainingDeclaration()
-        return !(baseDescriptor is AnonymousFunctionDescriptor || parent is ClassDescriptor && parent.getKind() == ClassKind.TRAIT)
+        return !(baseDescriptor is AnonymousFunctionDescriptor || parent is ClassDescriptor && parent.getKind() == ClassKind.INTERFACE)
     }
 
     override fun canChangeParameters(): Boolean {
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/ExtractableCodeDescriptor.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/ExtractableCodeDescriptor.kt
index f13acfa2df4..2a4989a0356 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/ExtractableCodeDescriptor.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/ExtractableCodeDescriptor.kt
@@ -347,7 +347,7 @@ enum class ExtractionTarget(val name: String) {
     companion object {
         fun checkNotTrait(descriptor: ExtractableCodeDescriptor): Boolean {
             val parent = descriptor.extractionData.targetSibling.getStrictParentOfType<JetDeclaration>()
-            return !(parent is JetClass && parent.isTrait())
+            return !(parent is JetClass && parent.isInterface())
         }
 
         fun checkSimpleBody(descriptor: ExtractableCodeDescriptor): Boolean {
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/extractableAnalysisUtil.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/extractableAnalysisUtil.kt
index 0a331daf9e2..e81e024c927 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/extractableAnalysisUtil.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/extractableAnalysisUtil.kt
@@ -802,7 +802,7 @@ fun ExtractionData.getDefaultVisibility(): String {
     if (!isVisibilityApplicable()) return ""
 
     val parent = targetSibling.getStrictParentOfType<JetDeclaration>()
-    if (parent is JetClass && parent.isTrait()) return ""
+    if (parent is JetClass && parent.isInterface()) return ""
 
     return "private"
 }
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceParameter/KotlinIntroduceParameterHandler.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceParameter/KotlinIntroduceParameterHandler.kt
index cf2c7190895..e11a03d9e71 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceParameter/KotlinIntroduceParameterHandler.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceParameter/KotlinIntroduceParameterHandler.kt
@@ -161,7 +161,7 @@ fun selectNewParameterContext(
 
                 (if (stopAt != null) parent.parents(withItself = false).takeWhile { it != stopAt } else parents)
                         .filter {
-                            ((it is JetClass && !it.isTrait() && it !is JetEnumEntry) || it is JetNamedFunction || it is JetSecondaryConstructor) &&
+                            ((it is JetClass && !it.isInterface() && it !is JetEnumEntry) || it is JetNamedFunction || it is JetSecondaryConstructor) &&
                             ((it as JetNamedDeclaration).getValueParameterList() != null || it.getNameIdentifier() != null)
                         }
                         .toList()
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/jetRefactoringUtil.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/jetRefactoringUtil.kt
index 3ad427cf5ad..631829f2236 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/jetRefactoringUtil.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/jetRefactoringUtil.kt
@@ -510,7 +510,7 @@ fun createJavaClass(klass: JetClass, targetClass: PsiClass): PsiMember {
     val factory = PsiElementFactory.SERVICE.getInstance(klass.getProject())
     val javaClassToAdd = when (kind) {
         ClassKind.CLASS -> factory.createClass(klass.getName())
-        ClassKind.TRAIT -> factory.createInterface(klass.getName())
+        ClassKind.INTERFACE -> factory.createInterface(klass.getName())
         ClassKind.ANNOTATION_CLASS -> factory.createAnnotationType(klass.getName())
         ClassKind.ENUM_CLASS -> factory.createEnum(klass.getName())
         else -> throw AssertionError("Unexpected class kind: ${klass.getElementTextWithContext()}")
diff --git a/idea/tests/org/jetbrains/kotlin/idea/stubs/JetStubsTest.java b/idea/tests/org/jetbrains/kotlin/idea/stubs/JetStubsTest.java
index b4f95b1a41e..c828c31a3cb 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/stubs/JetStubsTest.java
+++ b/idea/tests/org/jetbrains/kotlin/idea/stubs/JetStubsTest.java
@@ -50,6 +50,6 @@ public class JetStubsTest extends LightCodeInsightFixtureTestCase {
         List<JetDeclaration> declarations = ((JetFile) psiFile).getDeclarations();
         JetClass jetClass = (JetClass) declarations.get(0);
         KotlinClassStub stub = JetStubElementTypes.CLASS.createStub(jetClass, null);
-        assertEquals(true, stub.isTrait());
+        assertEquals(true, stub.isInterface());
     }
 }
diff --git a/js/js.translator/src/org/jetbrains/kotlin/js/translate/context/Namer.java b/js/js.translator/src/org/jetbrains/kotlin/js/translate/context/Namer.java
index fdf7542f84f..0ad20c54387 100644
--- a/js/js.translator/src/org/jetbrains/kotlin/js/translate/context/Namer.java
+++ b/js/js.translator/src/org/jetbrains/kotlin/js/translate/context/Namer.java
@@ -385,7 +385,7 @@ public final class Namer {
     @NotNull
     public JsExpression classCreateInvocation(@NotNull ClassDescriptor descriptor) {
         switch (descriptor.getKind()) {
-            case TRAIT:
+            case INTERFACE:
                 return traitCreationMethodReference();
             case ENUM_CLASS:
                 return enumClassCreationMethodReference();
diff --git a/js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/ClassTranslator.java b/js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/ClassTranslator.java
index 3e3c2bc7eba..a916bf86938 100644
--- a/js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/ClassTranslator.java
+++ b/js/js.translator/src/org/jetbrains/kotlin/js/translate/declaration/ClassTranslator.java
@@ -99,7 +99,7 @@ public final class ClassTranslator extends AbstractTranslator {
     }
 
     private boolean isTrait() {
-        return descriptor.getKind().equals(ClassKind.TRAIT);
+        return descriptor.getKind().equals(ClassKind.INTERFACE);
     }
 
     @NotNull
diff --git a/js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/JsDescriptorUtils.java b/js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/JsDescriptorUtils.java
index 16e5d6827f4..409867af32f 100644
--- a/js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/JsDescriptorUtils.java
+++ b/js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/JsDescriptorUtils.java
@@ -89,7 +89,7 @@ public final class JsDescriptorUtils {
                 ClassDescriptor classDescriptor = getClassDescriptorForType(type);
 
                 return !FAKE_CLASSES.contains(getFqNameSafe(classDescriptor).asString()) &&
-                       !(classDescriptor.getKind() == ClassKind.TRAIT && isNativeObject(classDescriptor));
+                       !(classDescriptor.getKind() == ClassKind.INTERFACE && isNativeObject(classDescriptor));
             }
         });
     }