bite your tongue
US /baɪt jʊər tʌŋ/
UK /baɪt jʊər tʌŋ/

1.
입을 다물다, 하고 싶은 말을 참다
to make a conscious effort to avoid saying something that you want to say, often because it would be inappropriate or cause trouble
:
•
I had to bite my tongue to keep from telling him what I really thought.
정말 하고 싶은 말을 참기 위해 입을 다물어야 했다.
•
She wanted to argue, but decided to bite her tongue.
그녀는 논쟁하고 싶었지만, 입을 다물기로 결정했다.