bite (one's) tongue

Translations
прикусить язык
She wanted to criticize him, but she bit her tongue.
Она хотела его раскритиковать, но прикусила язык.
Definitions
To refrain from speaking or to hold back one's words, especially to avoid saying something that might be inappropriate or hurtful.
Words
tongue

noun
язык
bite

verb
кусать