Green’s Dictionary of Slang

mush-head n.

[SE mush, anything soft and pulpy + -head sfx (1)]

(orig. US) a fool.

Young America (NY) 12 Jan. 81/1: The Laughable Farce [...] The Chief On Trial [...] Addlepate Mushhead (his Secretary).
Committees of Hse of Representatives 1863-64 40: Mr. Bonner confesses to having furnished the matter published, which leaves it very immaterial whether it was signed merchant, meddler, or mushhead.
[US]Anderson Intelligencer Anderson Court Ho., SC) 17 Nov. 2/2: There are several ‘mush heads’ round these diggings.
[US]F.H. Hart Sazerac Lying Club 160: ‘Smith?’ said the boy, ‘which Smith do you want? Let’s see – there’s big Smith and Little Smith [...] Mushhead Smith.’.
Bourbon News (Maysville, KY) 28 Apr. 3/6: ‘Scientist says the best brain food is corn meal’ If you wish to flatter a scientist [...] call him a mush-head — then run.
[UK]Barrère & Leland Dict. of Sl., Jargon and Cant II 74: Mush-head. A stupid witless fellow [DA].
[US]F. Norris Moran of the Lady Letty 39: I ain’t a mush-head.
[US]Greenville Times (MS) 9 Feb. 6/3: Aw, g’wan, youse ol’ mush-head, who’s a-hittin’ youse?
[US]S. Ford Torchy 108: Do you know what that mush-head of a Piddie was at?
F.K. Sechrist ‘The Psych. of Unconventional Lang.’ Pedagogical Seminary Dec. n.p.: Slang [...] knows how [...] to work the poppycock racket on any daffy squirt or dotty chucklehead or dippy mushhead, or any crazy kioodle or concatenated chump .
[US]Ogden Standard (UT) 27 Apr. 26/5: The poor mush-head who is enamoured of her refuses to play baseball at any place so distant [...] that he cannot see her at frequent intervals.
[US]Hecht & Bodenheim Cutie 65: He was a mush head and a wet smack.
R. Johns Pagany 69: Joe’s a cheap climber, and Frank’s a mushhead.
[US]J. Archibald ‘Skip Tracer Bullets’ in Popular Detective June 🌐 ‘You big mushhead,’ she yelped.
[US]W.R. Burnett Little Men, Big World 8: Reisman was getting goddamned superior since Mush Head broke down and let him have his say in a daily two-column spread.
[US]E. De Roo Big Rumble 7: ‘He’s just a mush-head,’ Larry joked.
[US]H. Rawson Dict. of Invective (1991) 261: mush-head, for someone who is none too bright.
S. Puchalski Slimetime 173: All the college girls are pretty brainless [...] and even the star, Cathy, seems like a mushhead most of the time.

In derivatives

mush-headed (adj.) (also mush-head)

stupid, foolish.

Nat. Normal (Cincinnati, OH) Jan. 119: Some senseless brutes broke up a colored schoo[...] The school was doing a good and legitimate work, and nothing but mush-headed prejudice was the cause.
[US]Memphis Dly Appeal (TN) 16 Mar. 2/2: The legislature should be made up of gentlemen of extended experience [...] not of musheaded weaklings.
[US]C.F. Lummis letter 5 Nov. in Byrkit Letters from the Southwest (1989) 73: There, you mush-headed idiots, fix up your darned old world to suit yourselves, if you’re so gee-whizzly smart.
[US]S.F. Call 20 Jan. 9/2: Better to be a determinate something than a mush-headed nothing.
[US]L.A. Herald 15 Nov. 5/3: Why, you mush-headed, old blankety-b-z-z-z-z, you’re losin’ your lawyer.
R. Cullum Way of Strong 294: The game isn’t worth it, fighting this mush-headed crowd who have to get other folks to think for ’em .
[US]Little Falls Herald (MN) 14 Feb. 5/4: There were a number of American Bolshevik sympathizers there. We referred to them as ‘mushheaded’.
[US]Berrey & Van den Bark Amer. Thes. Sl.
[US]E. Hoagland Cat Man 29: Old mealy mushhead winos whose hair grew long enough to braid.
R. Markley ‘Exterminate the Brutes: Fighting Back Against the Right’ on Electronic Book Rev. 🌐 The mush-headed right, at least since George Wallace, has accumulated political capital by tarring and feathering ‘pointy-headed intellectuals’.