Green’s Dictionary of Slang

(US) a fool.

1930		in Amer. Mercury Oct. 161: A guy don’ wanna wuyk, so he tuyns into a glom. Well, de idea is tuh teach de guy tuh be a useful citizen .
1950		Goldin et al. DAUL 82/2: Glom, n. 1. A worthless dolt; an exceedingly inept person.
1972		J. Mills Report to the Commissioner 106: ‘You know who resents you?’ she asks [...] ‘The gloms. The do-nothings. No matter how active you are, they’ll say, ‘Oh, she got in on a hook,’ explaining away their own incompetence.
1987		G.A. Fine With the Boys 167: In Beanville, a glom was an awkward kid, a creep.