make a clean breast

From the notion that secrets are figuratively hidden in the heart which is contained in the breast (“chest”), and that admitting them will cause the heart to become clean and pure.^[1]

• (Received Pronunciation) IPA^(key): /ˈmeɪk ə ˈkliːn bɹɛst/
• (General American) IPA^(key): /ˈmeɪk ə ˈklin bɹɛst/

• Audio (General Australian):

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make a clean breast (third-person singular simple present makes a clean breast, present participle making a clean breast, simple past and past participle made a clean breast)

1. (idiomatic) Often followed by of: to be honest about something; to confess.

   Synonyms: see Thesaurus:confess

   • 1753 October, “Extracts from the Trial of James Stewart, ”, in The Scots Magazine. , volume XV, Edinburgh: Printed by W. Sands, A. Murray, and J. Cochran, →OCLC, page 508:

     He preſſed him earneſtly to make a clean breaſt, and tell him all he knew of [Colin Roy Campbell of] Glenure's murder. To which Breck [i.e., Alan Breck Stewart] anſwered with an oath, that he had never ſeen Glenure dead or alive.

   • 1873, Jules Verne, “The Gulf Stream”, in , transl., Twenty Thousand Leagues under the Seas; , James R. Osgood edition, Boston, Mass.: Geo M Smith & Co., →OCLC, part II, page 278:

     "Master," he said that day to me, "this must come to an end. I must make a clean breast of it. This Nemo is leaving land and going up to the north. But I declare to you that I have had enough of the South Pole, and I will not follow him to the North."

   • 1886 January 5, Robert Louis Stevenson, “The Last Night”, in Strange Case of Dr Jekyll and Mr Hyde, London: Longmans, Green, and Co., →OCLC, page 78:

     'It is well, then, that we should be frank,' said the other. 'We both think more than we have said; let us make a clean breast. This masked figure that you saw, did you recognise it?'

   • 1906 January–October, Joseph Conrad, chapter X, in The Secret Agent: A Simple Tale, London: Methuen & Co., , published 1907, →OCLC; The Secret Agent: A Simple Tale (Collection of British Authors; 3995), copyright edition, Leipzig: Bernhard Tauchnitz, 1907, →OCLC, page 219:

     You know no doubt that most criminals at some time or other feel an irresistible need of confessing—of making a clean breast of it to somebody—to anybody.

   • 1915 August–September, John Buchan, “The Milkman Sets Out on His Travels”, in The Thirty-Nine Steps, Edinburgh; London: William Blackwood and Sons, published October 1915, →OCLC, page 38:

     I had lied to Paddock about him, and the whole thing looked desperately fishy. If I made a clean breast of it and told the police everything he had told me, they would simply laugh at me.

   • 2003, Tom DeMarco, Timothy Lister, “The Case for Risk Management”, in Waltzing with Bears: Managing Risk on Software Projects, New York, N.Y.: Dorset House Publishing, published 2013, →ISBN, part I (Why), page 30:

     Instead, imagine that a software project manager approaches you and makes a clean breast of his uncertainty about your proposed project: "Look, there are unknowns here, and we have catalogued the following eleven of them."

• get off one's chest

• “to make a clean breast” under “breast, n.”, in OED Online ⁠, Oxford: Oxford University Press, 1888.
• “make a clean breast of something, phrase”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.