Green’s Dictionary of Slang

a mild, blasphemous oath, a euph. for God’s wounds.

1550		Udall Ralph Roister Doister I iv: Kock’s nownes, what meanest thou man? tut, a whistle.
1667		Dryden Sir Martin Mar-all IV i: By Cox-nowns, it was an ill-natur’d Part.
1672		J. Phillips Maronides (1678) V 45: This vow attested with Cuds-nowns.
1675		T. Duffet Mock Tempest I i: Nounz, stir about, or I’le beat thy brains out with my Bottle.
1699		N. Ward London Spy XII 290: Cats Nouns, says the Gentleman, your Cooks are all Blockheads.
1709		N. Ward Compleat and Humorous Account of Remarkable Clubs (1756) 288: Nouns, says Moll Swank, I think my Belly begins to swell two or three Gallons before its Time.
1733		Laugh and Be Fat 6: Nouns, says the Priest, I am resolv’d the Impudent Rogue shall not Cozen me of my Dinner.
1787		R. Tyler Contrast V i: I can’t laugh for the blood and nowns of me.
1822		(con. early 17C) W. Scott Fortunes of Nigel I 40: Nouns, man, the Whitehall gateways were planned by the great Holbein.
1825		W. Scott Journal 18 Oct. (1972) 215: (Cocksnowns!) I shall never be able to take the trouble.