ALL meanings of mum's the word
mum
M m - adjective mum's the word silent; not saying a word: to keep mum. 1
- idioms mum's the word 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. 1
- noun mum's the word silence or secrecy is to be observed 0
- noun mum's the word say nothing 0