Greek has an adjective ἀνυπόκριτος that has been translated as unfeigned or genuine.
If this word was translated literally it might be unactorly or not dramatically or by a phrase not like a stage performer or actor or even unmasked since actors and performers in Greek and Roman Dramas wore masks.
Here's a quote that includes that word.
Romans 12:9 ἡ ἀγάπη ἀνυπόκριτος
Let love be genuine or in some older versions unfeigned is used.
Love Agape must be an sincere action not an act.
This word is also used again in 2 Corinthians 6.6