Definition of mum's the word
—used to say that some information is being kept secret or should be kept secret We want her birthday party to be a surprise, so mum's the word.
Is it mums the word or mum's the word?
Note that the word mum's in mum's the word is a contraction of mum is, and therefore requires an apostrophe.
Where did Mums the word come from?
The 'mum' in the expression 'mum's the word' is derived from the humming sound a closed mouth makes, indicating an inability or unwillingness to speak. ... You'll find it in Shakespeare's Henry VI, Part 2: “Seal up your lips and give no words but mum.”
