guard one's tongue

present singular third person guards one's tongue · participle present guarding one's tongue · participle past guarded one's tongue · past guarded one's tongue

1. To be careful in what one says; to avoid divulging information or speaking in a way considered to be inappropriate or offensive.

   Oh, Howard, Howard, the things you have uttered when you were forgetting to guard your tongue, have betrayed you.

   1892, Mark Twain [pseudonym; Samuel Langhorne Clemens], chapter XXIII, in The American Claimant, New York, N.Y.: Charles L[uther] Webster & Co., →OCLC, page 241

   3 more examples

   1696, Aphra Behn, “Love-Letters to a Gentleman,” Letter 3, in All the Histories and Novels Written by the Late Ingenious Mrs. Behn, London: Samuel Briscoe, p. 47, […] though I scorn to guard my Tongue, as hoping ’twill never offend willingly; yet I can, with much adoe, hold it, when I have a great mind to say a thousand things I know will be taken in an ill sence.

   […] of course it is a little out of character to call upon me to guard my tongue, when it is the privilege of a freeman to speak his mind […]

   1793, John Trusler, chapter 36, in Life; or, The Adventures of William Ramble, Esq., volume 3, London: for the author, page 86

   But in spite of the affection she felt for her charming mother-in-law, Arnon had extended no confidences. Her father had warned her to guard her tongue in the presence of these people.

   1948, Lloyd C. Douglas, chapter 2, in The Big Fisherman, Toronto: Thomas Allen, page 30