Verb: button up
- Refuse to talk or stop talking; fall silent
"The suspect buttoned up when questioned by the police";
- close up, clam up [informal], dummy up [N. Amer, informal], shut up, belt up [Brit, informal], be quiet, keep mum [informal]
- Fasten or close completely
"Button up your coat, it's cold outside"
Derived forms: buttoning up, buttoned up, buttons up