mum's the word

Idioms  

1. 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.”

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Example Sentences

While mum’s the word for now, Mosher hopes to soon announce good news on the horizon for fans of the restaurant.

From Seattle Times • Nov. 25, 2023

The short answer: For now, mum’s the word.

From Washington Times • Feb. 5, 2019

Davis calls spots mums, "because when people ask what I was using, I'd always say, �Mums � mum's the word.'"

From Time Magazine Archive

Then he says to the duke, "We got to jest swaller it and say noth'n': mum's the word for us."

From The Adventures of Huckleberry Finn Tom Sawyer's Comrade by Twain, Mark

He seemed to have taken quite a fancy to her, but mum's the word, my dear.

From The Time of Roses by Meade, L. T.