diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt
index af044568ae6..33fda2c6791 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt
@@ -15,7 +15,6 @@ import org.jetbrains.kotlin.descriptors.annotations.KotlinTarget
 import org.jetbrains.kotlin.descriptors.annotations.KotlinTarget.*
 import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
-import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.lexer.KtTokens.*
 import org.jetbrains.kotlin.psi.KtClassOrObject
 import org.jetbrains.kotlin.psi.KtDeclarationWithBody
@@ -119,7 +118,7 @@ object ModifierCheckerCore {
         EXPECT_KEYWORD to listOf(LanguageFeature.MultiPlatformProjects),
         ACTUAL_KEYWORD to listOf(LanguageFeature.MultiPlatformProjects),
         LATEINIT_KEYWORD to listOf(LanguageFeature.LateinitTopLevelProperties, LanguageFeature.LateinitLocalVariables),
-        FUN_KEYWORD to listOf(LanguageFeature.FunctionInterfaceConversion)
+        FUN_KEYWORD to listOf(LanguageFeature.FunctionalInterfaceConversion)
     )
 
     private val featureDependenciesTargets = mapOf(
@@ -127,7 +126,7 @@ object ModifierCheckerCore {
         LanguageFeature.LateinitLocalVariables to setOf(LOCAL_VARIABLE),
         LanguageFeature.LateinitTopLevelProperties to setOf(TOP_LEVEL_PROPERTY),
         LanguageFeature.InlineClasses to setOf(CLASS_ONLY),
-        LanguageFeature.FunctionInterfaceConversion to setOf(INTERFACE)
+        LanguageFeature.FunctionalInterfaceConversion to setOf(INTERFACE)
     )
 
     // NOTE: deprecated targets must be possible!
diff --git a/compiler/testData/codegen/box/funInterface/basicFunInterface.kt b/compiler/testData/codegen/box/funInterface/basicFunInterface.kt
index d964e949879..f937fe65b99 100644
--- a/compiler/testData/codegen/box/funInterface/basicFunInterface.kt
+++ b/compiler/testData/codegen/box/funInterface/basicFunInterface.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +FunctionInterfaceConversion
+// !LANGUAGE: +FunctionalInterfaceConversion
 
 fun interface Foo {
     fun invoke(): String
diff --git a/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt b/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt
index d8561aebbd5..b13d2bb2e25 100644
--- a/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt
+++ b/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 
 fun interface Foo {
     fun invoke(): String
diff --git a/compiler/testData/codegen/box/funInterface/castFromAny.kt b/compiler/testData/codegen/box/funInterface/castFromAny.kt
index fa48ed88b42..8253e899096 100644
--- a/compiler/testData/codegen/box/funInterface/castFromAny.kt
+++ b/compiler/testData/codegen/box/funInterface/castFromAny.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 
 fun interface KRunnable {
     fun invoke()
diff --git a/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt b/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt
index afae7d8c119..30e520ea6dc 100644
--- a/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt
+++ b/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // WITH_RUNTIME
 
 fun interface MyRunnable {
diff --git a/compiler/testData/codegen/box/funInterface/nullableSam.kt b/compiler/testData/codegen/box/funInterface/nullableSam.kt
index 852e9381c28..cea63cb7e88 100644
--- a/compiler/testData/codegen/box/funInterface/nullableSam.kt
+++ b/compiler/testData/codegen/box/funInterface/nullableSam.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 
diff --git a/compiler/testData/codegen/box/funInterface/partialSam.kt b/compiler/testData/codegen/box/funInterface/partialSam.kt
index 6130c1b80be..f33c10526c2 100644
--- a/compiler/testData/codegen/box/funInterface/partialSam.kt
+++ b/compiler/testData/codegen/box/funInterface/partialSam.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // WITH_RUNTIME
 
 fun interface Fn<T, R> {
diff --git a/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt b/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt
index 9d156c2c881..f436ccc2be0 100644
--- a/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt
+++ b/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
diff --git a/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt b/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt
index 311c70f7b83..81845f27bb3 100644
--- a/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt
+++ b/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // WITH_COROUTINES
 // WITH_RUNTIME
 
diff --git a/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt b/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt
index 01b95bde8f5..06c13da3428 100644
--- a/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt
+++ b/compiler/testData/compileKotlinAgainstKotlin/useDeserializedFunInterface.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 
 // FILE: A.kt
 
diff --git a/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.kt b/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.kt
index b7ade62d514..5f0dcc62da6 100644
--- a/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +FunctionInterfaceConversion
+// !LANGUAGE: +FunctionalInterfaceConversion
 
 fun interface Foo {
     fun invoke()
diff --git a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.kt b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.kt
index 52e3e01c232..bfbea8fb9da 100644
--- a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +FunctionInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
 fun interface Foo {
diff --git a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.kt b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.kt
index 4bad102597d..bb4754e8b80 100644
--- a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: -FunctionInterfaceConversion
+// !LANGUAGE: -FunctionalInterfaceConversion
 
 <!UNSUPPORTED_FEATURE!>fun<!> interface Foo {
     fun invoke()
diff --git a/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.kt b/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.kt
index c4b9340ea17..699fc41cc74 100644
--- a/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionInterfaceConversion
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionalInterfaceConversion
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
 fun interface KRunnable {
diff --git a/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.kt b/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.kt
index 39dec07369e..d1e450a1e9c 100644
--- a/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionInterfaceConversion
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionalInterfaceConversion
 // !CHECK_TYPE
 
 fun interface F<S> {
diff --git a/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.kt b/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.kt
index 5690aa82031..5a97a54eede 100644
--- a/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionInterfaceConversion
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionalInterfaceConversion
 
 interface J {
     fun foo1(r: KRunnable)
diff --git a/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.kt b/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.kt
index 398c0368ff9..bffd4d08f24 100644
--- a/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.kt
@@ -1,4 +1,4 @@
-// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionInterfaceConversion
+// !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument +FunctionalInterfaceConversion
 // !DIAGNOSTICS: -UNUSED_PARAMETER -NOTHING_TO_INLINE
 
 fun interface SuspendRunnable {
diff --git a/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt b/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt
index c4cdd8e27e1..10433faa2bf 100644
--- a/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt
+++ b/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt
@@ -125,7 +125,7 @@ enum class LanguageFeature(
     ProperVisibilityForCompanionObjectInstanceField(KOTLIN_1_4, kind = BUG_FIX),
     DoNotGenerateThrowsForDelegatedKotlinMembers(KOTLIN_1_4),
     ProperIeee754Comparisons(KOTLIN_1_4, kind = BUG_FIX),
-    FunctionInterfaceConversion(KOTLIN_1_4, kind = UNSTABLE_FEATURE),
+    FunctionalInterfaceConversion(KOTLIN_1_4, kind = UNSTABLE_FEATURE),
 
     // Temporarily disabled, see KT-27084/KT-22379
     SoundSmartcastFromLoopConditionForLoopAssignedVariables(sinceVersion = null, kind = BUG_FIX),