Green’s Dictionary of Slang

nincompoop n.

also nickumpoop, nincumpoop, nink-a-poop, ninkompoop, ninkumpupe, ninny-cum-poop, ninnicum
[‘one who never saw his wife’s cunt n. (1)’ (Grose 1785); Grose (c.1786) suggests ‘+ perhaps corruption of non compus’]

1. a fool, a simpleton; a suitor who lacks self-confidence; a hen-pecked husband.

[UK]T. Shadwell Epsom Wells II i: Yes, you Nincompoop, you are a pretty Fellow to please a Woman indeed.
[UK]Poor Robin True Character of a Scold 5: She [...] has either quite forgot his Name, or else she likes it not; which makes her Rebaptize him with more noble Titles, as White-liver’d Raskal, Drunken sot, Sneaking Ninkompoop, or pitiful lowsy Tom Farthing.
[UK]Fifteen Real Comforts of Matrimony 76: Nor is the woman to be blam’d for taking pepper i’ the nose, to see a Nickapoop revealing the secrets of his wife to his own ignominy.
[UK]D’Urfey Comical Hist. of Don Quixote Pt III V i: What! take away your Wife’s Money the first Week of her Marriage? Ah, Nincompoop.
[UK]B.E. Dict. Canting Crew n.p.: Nickum-poop, a Fool, also a silly soft, Uxorious Fellow.
[UK]N. Ward Hudibras Redivivus I:10 9: Thus did the sundry Female Troops, / Conducted by their Nincompoops, / In scatt’ring Numbers, jostling met.
[UK]‘Phoebe Crackenthorpe’ Female Tatler (1992) (26) 64: A count! – The wives are not able to eat a bit more. ‘Dear Nincompoop, present our Deborah to the Count.’.
[UK]W. King York Spy 31: She posts to the Metropolis, and after his departure, is entertain’d by a young Nink-a-poop she has indulg’d.
[UK]New Canting Dict. n.p.: Nickum-poop, a Fool, also a silly soft, Uxorious Fellow.
[UK]C. Coffey Boarding-School Dramatis Personae: Alderman Nincompoop, A sneaking Uxorious Citizen.
[UK]Bailey Universal Etym. Eng. Dict. [as cit. 1725].
[UK]Smollett Peregrine Pickle (1964) 424: Odds plague! you nincompoop, (cried she) you have fumbled so long about the pot, that I have drenched myself all over.
[UK]Foote Mayor of Garrat in Works (1799) I 174: sneak: I come lovy. [...] bruin: Trot, nincompoop.
[US]‘Andrew Barton’ Disappointment III i: Ricketts is a nincompoop to you honey!
[UK]Derby Mercury 8 Sept. 4/2: Warwick Races [...] Mr Vernon’s brown horse Pioneer 2dr. Lord Craven’s Nincompoop 3dr.
[Ind]Hicky’s Bengal Gaz. 15-22 Dec. n.p.: TATOES Yeat’s Black H. Nincumpoop lost.
[UK]Grose Classical Dict. of the Vulgar Tongue n.p.: Nickumpoop, or nincumpoop, a foolish fellow; also one who never saw his wife’s ****.
[UK]G. Hangar Life, Adventures and Opinions II 75: Lady A-- told Lady B--, that her husband was a cuckold and a nincompoop.
[UK]J. Poole Hamlet Travestie II ii: Why, look ye, what a nincompoop you’d make me.
[Scot]W. Scott Kenilworth I 217: Wayland Smith expressed, by every contemptuous epithet [...] his utter scorn for the nincompoop, who stuck his head under his wife’s apron-string.
[UK]‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 126: Nincum-poop, a term of derision, applied by a young lass to her lover, who presses not his suit with vigour enough.
[US]A. Greene Life and Adventures of Dr Dodimus Duckworth II 98: He can’t read, write, nor spell – he’s the merest nincompoop that ever mixed a draught.
[UK]E. Howard Jack Ashore II 120: A sorry nincompoop – he is a contemptible ass.
[US]Gleaner (Manchester, NH) 29 Apr. n.p.: The place which defies all the nincompoops or corporation lickspittles.
[US]Mountain Sentinel (Ebensburg, PA) 19 Sept. 1/6: Poor fool! [...] There is a possibility of his making a nincompoop of himself.
[US]Life in Boston & N.Y. (Boston, MA) 23 Aug. n.p.: That half-witted ninnicum.
[UK]C. Reade It Is Never Too Late to Mend II 340: Ye ninny-cum-poops!
[UK]R.S. Surtees Ask Mamma 241: A landlord had better lend his land to a cheesemonger [...] a draper, anybody with energy and capital, rather than to one of these self-sufficient, dawdling nincompoops.
[UK]‘George Eliot’ Mill on the Floss (1985) I 153: He had described uncle Pullet as a nincompoop.
[Ind]‘Aliph Cheem’ Lays of Ind (1905) 94: ‘He’s an impudent nincompoop!’.
[US]Atlanta Constitution 1 Apr. 2/3: The Hon. Secor Robertson, late the able nincompoop of the navy.
[Aus]Bulletin (Sydney) 22 Jan. 5/4: [A] man whose common sense will not allow him to perceive beauties where none exist, and to ‘melt in pure delight’ over the maudlin rubbish of ‘nincompoops’ whose proper sphere is either the barber’s-shop or the draper’s counter.
[UK]Bird o’ Freedom 1 Jan. 3/2: Who was the nincompoop with her in the morning? A mere blind.
[UK]A. Bennett Grand Babylon Hotel 114: I am not implicated in the murder of this unfortunate nincompoop.
[NZ]N.Z. Truth 26 Jan. 6/8: The virtuous and angry spinsters who have had their honest work thrown in their faces by an insulting nincompoop.
[UK]J. Buchan Mr Standfast (1930) 617: Ivery and Gresson took me for a well-meaning nincompoop.
[UK]Wodehouse Carry on, Jeeves 73: He said I was a brainless nincompoop.
[Aus]K.S. Prichard Haxby’s Circus 98: God-damned nincompoop, that he is!
[Aus]X. Herbert Capricornia (1939) 115: Oscar cocked his head, rather surprised to hear that this nincompoop was capable of arranging anything so wise.
[US]H. Miller Sexus (1969) 25: Another nincompoop who had written a highly succesful book about Jesus-the-carpenter.
[UK]M.F. Caulfield Black City 52: He’s trying to put over another puff for those marble-mouthed nincompoops across the water.
[UK]I. & P. Opie Lore and Lang. of Schoolchildren (1977) 409: When the person comes to the door we make faces, and shout names like you old haggis, you old ninkumpupe.
[UK]Wodehouse Jeeves in the Offing 78: She wanted to tell me you were a nincompoop.
[US]G. Cuomo Among Thieves 183: Kale doesn’t understand anything. He’s a nincompoop.
[US](con. 1916) G. Swarthout Tin Lizzie Troop (1978) 145: Not only have those nincompoops of yours entered the Republic of Mexico [...] they have entered it in automobiles!
[UK]Beano Special No. 13 n.p.: Idiot! Nincompoop! Pest!
[UK]Indep. on Sun. 12 Dec. 28: The artist whom Brian Sewell called a ‘cloth-capped nincompoop’.
[UK]Guardian Weekend 25 Mar. 3: The origin of the word ‘nincompoop’ is unclear.
[UK]Indep. 27 Dec. 13/5: A harpie in trousers and a nincompoop.

2. in attrib. use of sense 1.

[US]Ely’s Hawk & Buzzard (NY) 15 Mar. 1/1: A certain nincompoop barber.
[UK]Sheffield Indep. 31 July 7/2: One guardian was calling two others a couple of ‘nincompoop turncoats’.
[UK]Reynolds’s Newspaper 25 Sept. 4/4: They laugh at our little arm with its nincompoop officers.
[UK]J. Meades Empty Wigs (t/s) 173: [A] succession of nincompoop stewards and superintendents who weren’t up to the job .

In derivatives

nincompoopery (n.)

foolishness.

[US]S. Lewis Arrowsmith 142: Were they, in their present condition of nincompoopery, worth any sort of attention?