biting one's tongue

Verb

bite one's tongue (third-person singular simple present bites one's tongue, present participle biting one's tongue, simple past bit one's tongue, past participle bitten one's tongue)

1. (idiomatic, intransitive) To resist the urge to speak out, especially in order to avoid saying something inappropriate or likely to cause a dispute.
   • She wanted to go see a movie called Gigi, which I was not too thrilled about. But being a gentleman, I bit my tongue and said, “Okay.”2011, Mike Pappas, Growing Up the Greek Way in the Big Apple, page 103

   Synonyms:

   bite one's lip