Green’s Dictionary of Slang

stupid; thus boneheadedness, stupidity.

1864		A.J. Dickson Across Plains (1929) 143: If some boneheaded mule displayed characteristic traits, the muleskinner was very expert with his long lash [DAE].
1903		Smart Set IX. 96: You talk like a bone-headed fool! [DAE].
1910		Wodehouse Gentleman of Leisure Ch. xxi: You bone-headed bachelors make me sick.
1914		R. Lardner You Know Me Al (1984) 169: It is a cinch that none of them bonehead nurses would have knew what to do.
1915		Wash. Herald (DC) 19 Oct. 1/7: The English-Americans are narrow, pig-headed, bone-headed and mushheaded [...] Virginia was the home of fanataicism and others the homes of bone-headedness.
1918		Eve. Dispatch 28 June 1/5: Well, of all the bone-headed mugwumps, you take the petzel [sic].
1921		N. Putnam West Broadway 215: They are absolutely friendly except when the boneheaded Government sends soldiers in to take their children away to school by force.
1922		Times (Shreveport, LA) 29 Oct. 39/1: It wasn’t blind love — it was just bonehead infatuation.
1923		H.C. Witwer Fighting Blood 305: The Rags pulls the boss boner of a lifetime devoted to making boneheaded plays.
1927		E. Pound letter 24 Sept. in Paige (1971) 212: He will endow any number of ‘institutions’ employing any number of boneheaded dullards with ‘degrees,’ in order that they may still further befuddle the young.
1932		D.L. Sayers Have His Carcase 242: Take off that vulgar and idiotic hat and tell me who this low-down, bone-headed, bird-witted, dissipated murderer is.
1938		X. Herbert Capricornia (1939) 391: You’re the sorter bonehead barsted that looks on fellers like us what have a different kinder philosophy to you as blunny criminals.
1940		(con. 1918) S.J. Simonsen Soldier Bill 93: The bone-headed stunts pulled by some of the officers in charge.
1952		Lait & Mortimer USA Confidential 88: She was making one of her typical boneheaded speeches.
1961		Brides in Love I:25 July 23: My boneheaded husband thinks she means that phoney smile!
1968		L. Barrett Rastafarians (1977) 236: Dem call dem paper tigers / Dem call dem bonehead dunces in the Queens court.
1974		G.F. Newman You Flash Bastard 245: Your new chief, Terry, is obstinate, boneheaded, wilfully obstructive.
1979		(con. c.1970) G. Hasford Short Timers (1985) 162: When I’m a civilian first class and you’re a bonehead funny gunny I’ll buy you a beer.
1992		P. Slabolepszy ‘Return of Elvis’ Mooi Street (1994) 314: He never had to try to convince a bone-headed boss.
1999		Observer Rev. 21 Nov. 3: I thought it was a real bonehead move on her part.
2000		Indep. on Sun. Rev. 27 Feb. 55: From boneheaded bouncers to slick and shady rude boys.
2006		C. Hiaasen Nature Girl 123: Meanwhile your bonehead husband and his fake-Fonda lady friend just carried their bags into a mobile home.
2008		E. Drew in N.Y. Rev. of Books 17 Apr. 14/4: An action that Obama has numerous times described as ‘a mistake,’ and ‘boneheaded’.
2015		S. King Finders Keepers (2016) 185: The bonehead move was not quitting while I was ahead.
2016		Guardian 2 May 23/3: Those responsible for bone-headed eurozone policies carry on regardless.