Green’s Dictionary of Slang

1. (US) a stupid person; thus as a term of address.

1929		(con. 1917–18) C. MacArthur War Bugs 140: We bawled them out for a lot of meat-heads.
1953		‘Curt Cannon’ ‘The Death of Me’ in I Like ’Em Tough (1958) 101: You must take me for a meathead, Semmler.
1965		(con. 1944) E.M. Nathanson Dirty Dozen (2002) 359: I’ve always been glad it was me and not some meathead you talked to.
1974		(con. 1940s) E. Thompson Tattoo (1977) 173: Hey, that’s what I’ve been trying to tell a bunch of Missouri, Iowa and Oklahoma meatheads since I’ve been in.
1989		G. Tate ‘Adeva’ in Flyboy in the Buttermilk (1992) 113: She excused herself at one point to cold dismiss some meathead acting all loud.
1992		K. Lette Llama Parlour 199: They’re in a kind of limbo-land. Not the macho meatheads they were brought up to be, or the Male Feminists they claim to be on telly chat shows.
2001		K. Sampson Outlaws (ms.) 142: Al Stanton of the purple SLK. Meathead. Fucking bully.
2004		Mad mag. July 45: Lawsuits that pour in from bimbos and meatheads.
2005		L. Redhead Rubdown [ebook] Meatheads [...] Couldn’t handle that we were smarter than they were.
2011		J.J. Connolly Viva La Madness 331: What was I thinking of? Getting that meathead Santos over here.
2014		E. Kurz ‘Nothing You Can Do’ in ThugLit Mar. [ebook] The meatheads in the front box who gave him the shiner.
2015		G. Disher Heat [ebook] ‘It’s not unusual for serving and disgraced police officers to share certain interests with the meatheads who join bikie gangs’.
2022		Twitter 3 Aug. 🌐 So unprofessional to refer to people in the legal profession using such a ridiculous cliché [i.e. ‘lefty lawyers’] that only appeals to the thickest, rightwing meatheads.

2. a general term of abuse.

1949		W.R. Burnett Asphalt Jungle in Four Novels (1984) 144: Look, meathead [...] no use us being sore at each other.
1953		L. Uris Battle Cry (1964) 117: O.K., you meatheads, take off your packs.
1999		USA Today 23 Dec. 04D: While Buffy hasn’t yet had a word achieve the breakout status of Seinfeld’s ‘yada, yada,’ or All in the Family’s ‘meathead,’ it is a rich source.
2012		(con. 1954) ‘Jack Tunney’ Tomato Can Comeback [ebook] ‘My hand is pretty sore.’ ‘You mighta broke it on that meathead’s face’.