- silent; not saying a word: to keep mum.
- say nothing! be silent!
- mum's the word, do not reveal what you know (about something); keep silent: Mum's the word, or the surprise party won't be a surprise.
Origin of mum1
- mainly British an informal word for mother 1
- keeping information to oneself; silent
- mum's the word silence or secrecy is to be observed
- (intr) to act in a mummer's play
- British obsolete a type of beer made from cereals, beans, etc
Word Origin and History for mum's the word
"be silent," 1560s, from Middle English mum, mom (late 14c.), inarticulate closed-mouth sound, indicative of unwillingness or inability to speak. As an adjective meaning "secret" from 1520s. Phrase mum's the word is first recorded 1704.
abbreviation of chrysanthemum, first attested 1915 in the jargon of gardeners.
Idioms and Phrases with mum's the word
mum's the word
Say nothing about this, it's a secret, as in Mum's the word on tonight's surprise party. This expression dates from about 1700, but mum, meaning “silence,” is much older. In 2 Henry VI (1:2) Shakespeare wrote, “Seal up your lips, and give no words but mum.”