belt up belt-tightening • beltway · · · Info · Definitions · Synonyms · Characters · · belt up · · Text Common · · Latin · · Scripts 7 · · Length 2 · · Syllables Definitions · · · (verb) refuse to talk or stop talking; fall silent. Synonyms: close up, clam up, dummy up, shut up, belt up, button up, be quiet, keep mum. Example: "The children shut up when their father approached." · · Verb Definition 1 Synonyms · · · close up · · Synonym 1 clam up · · Synonym 2 dummy up · · Synonym 3 shut up · · Synonym 4 button up · · Synonym 5 be quiet · · Synonym 6 keep mum · · Synonym 7 Characters · · space U+0020 b latin small letter b U+0062 e latin small letter e U+0065 l latin small letter l U+006C p latin small letter p U+0070 t latin small letter t U+0074 u latin small letter u U+0075