not breathe a word

Idioms  

1. Not reveal a secret, keep concealed, as in You must promise not to breathe a word of what I'm about to tell you. This phrase relies on the verb breathe as meaning “to utter,” a usage dating from the late 1500s.

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Example Sentences

Limit visits to holidays and weekends, bounce the grandkids on his knee, not breathe a word about business or affairs of state.

From The Guardian • Nov. 22, 2016

Molly begs Sam to leave that out of the report and not breathe a word of it to anyone, at least until she figures out what happened while she was supposedly alone in space.

From Washington Post

It is not good, my compatriots, that you should not breathe a word of it to anybody, not even to your own soul for fear of having to judge yourself.

From Time Magazine Archive

You will not breathe a word, of course, Harry.

From The Sailor by Snaith, J. C.

"That's the two hundred; put it in your pocket; I want you to promise that you'll not breathe a word to any one about the money having come from me."

From A Woman Perfected by Marsh, Richard