Green’s Dictionary of Slang

cauliflower n.2

[visual resemblance]

1. [late 18C–early 19C] a large white wig ‘such as is commonly worn by the dignified clergy, and was formerly by physicians’ (Grose, 1785); also attrib.

2. [early–mid-19C] one who wears powder in their hair.

3. [late 19C+] the foaming top of a newly poured glass of beer.

4. [20C+] a ‘cauliflower ear’, the sign of a boxer whose ears have taken too many punches to retain their original shape [abbr. SE].

5. [1910s] in ext. use of sense 3, the head.

6. [1940s] by metonymy, based on sense 4, a boxer.

7. attrib. use of sense 6, pertaining to prizefighting.

SE in slang uses

In compounds

cauliflower cock (n.) [? the use of vegetables as dildos, although not, presumably, a cauliflower]

[2000s] (US black) a dildo.