Green’s Dictionary of Slang

stupid, with a small brain.

1888		Morn. Appeal (Carson City, NV) 25 Dec. 3/4: It will seem rather hard if so bright [...] a man as Von Read is beaten [...] by a lot of pinheaded, jacklegged little gallinippers.
1899		Bismarck Wkly Tibune (ND) 24 Mar. 7/4: The pinheaded editor who wrote that is utterly incapable of understanding.
1902		Ade Forty Modern Fables 67: Is it not Sad to see a pin-headed Rake dissipating a Large Fortune?
1904		Sydney Sportsman (Surry Hills, NSW) 14 Dec. 8/6: [A]pin-headed noodle, who had a kink for manufacturing stupid jokes.
1908		‘O. Henry’ ‘The Clarion Call’ in Voice of the City (1915) 194: They send a lot of pin-head reporters around to the scene.
1910		Sporting Times 27 Aug. 1/2: That sort o’ bluff may go with some o’ the pin-head conks, but we know better.
1916		J. Lait ‘Annye’s Ma’ in Beef, Iron and Wine (1917) 281: He asks you what you can expect from such a soused manager and such a pinhead press agent.
1918		‘Commander’ Clear the Decks! 77: Take your eyes off me, you pin-headed plebe, and thin out!
1922		R. McAlmon ‘Summer’ in A Hasty Bunch 234: They were whining sorts, and both pinheaded old people.
1930		J. Lait Gangster Girl 85: I’m just a pinheaded dame, chasin’ pleasure.
1950		J. Weidman Price Is Right 188: Doesn’t that pinheaded idiot understand a simple thing like --?
1960		C. MacInnes Mr Love and Justice (1964) 68: Others invested in huge wardrobes or fast cars: but this, except among the pin-headed, was considered most unwise.
1966		H. Porter Paper Chase 247: The man with the walking-stick listening to the waves nudging pin-headedly at the threadbare sands.
1973		M. Harris Angry Eye 230: The students shamble out of the open classroom at school to the open situation of the university, intellectually pinheaded.
1987		C. Hiaasen Double Whammy (1990) 210: Maybe the pinhead hydrologist could work a few miracles.
1988		M. Atwood Cat’s Eye (1989) 218: He doesn’t want me to be a pin-headed fuzzbrain.
1990		(con. c.1970) G. Hasford Phantom Blooper 78: You pinheaded no-brained foreskin-chewing pogey bait maggots, you are lower than worm life!
2002		S. Maloney Something Fishy (2006) 225: And where were the pinhead pigs?