mum's the word
phrase
informal
—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.
Cite this Entry
“Mum's the word.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mum%27s%20the%20word. Accessed 15 Mar. 2026.
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