Green’s Dictionary of Slang

1. a fool, a stupid person.

1697		Behn False Count IV ii: I defie thee, thou foul filthy Cabbage head, for I am mad, and will be valiant.
1786		J. O’Keeffe Wicklow Mountains 44: I’m neither a potatoe nor a turnip, old cabbage head.
1862		J.R. Lowell Biglow Papers 2nd Ser. 228: For take my word for’t, when all’s come an’ past, / The cabbage-heads’ll cair the day at last; / Th’ aint been a meetin’ since the world begun, / But they made (raw or bil’d ones) ten to one.
1872		Leavenworth Wkly Times (KS) 13 June 1/3: We cannot take lunk-heads, chowder-heads and cabbage-heads as figure heads this campaign.
1887		G. Horncastle ‘Right Before the Missis Too’ 🎵 I’ve had a dreadful row / All through a chum named Tommy Sheen, / I ought to call him cabbage-head, / He is so very green.
1891		Witchita Dly Eagle (KS) 6 Mar. 4/2: When the final bill is passed, / And parting words are said, / Each ‘Hayseed’ and each ‘Cocklebur’ / Appears a ‘Cabbagehead’.
1895		Crowe Aus. Sl. Dict. 14: Cabbage Head, a soft-headed person.
1908		Salt Lake Herald (UT) 6 Oct. 2/5: What! [...] that girl called me a cabbagehead!
1913		A. Irvine My Lady of the Chimney Corner 78: Yer blinked, ye cabbage head.
1922		Clayton News (NM) 3 Feb. 2/4: At a flash of the brain it must shoot a wireless message into cabbagehead or king.
1929		S. Ornitz Haunch Paunch and Jowl 241: My chin seems to start at my cheek-bones. Hogshead belly and cabbage head.
1956		Joe Clay ‘Jelly Bean’ 🎵 Did you mean Jelly Bean? Yeah, what you said Cabbage Head.
1960		Mad mag. Jan. 19: Any cabbage-head knows that!
1964		R. Abrahams Deep Down In The Jungle 45: What do you mean jelly bean? / What I said, cabbage head.

2. (Aus.) a native/inhabitant of Victoria [? misreading of sense 1].

1895

Indianapolis Jrnl 30 June 14/4: Cabbagehead is New South Wales for a Victorian.

3. (US drugs) someone who will try any drug.

2001

ONDCP Street Terms 5: Cabbage head — An individual who will use or experiment with any kind of drug.