phony smile

Translations
фальшивая улыбка
She gave a phony smile to hide her true feelings.
Она сделала фальшивую улыбку, чтобы скрыть свои истинные чувства.
Definitions
A phony smile is a smile that is insincere or fake, often used to mask true feelings or emotions, typically to convey friendliness or politeness without genuine warmth or happiness.