thumbhead
someone whose neck is as wide or wider than his/her head so that the whole head-neck region looks like a giant thumb. A weak chin might add to this effect.
I'd never go out with him because he's a thumbhead.
Thumbhead
A big muscular bald man, typically seen at gyms or seen through a window doing meal prep.
Look at that thumbhead! He just pumps and pumps and there’s other thumbheads pumping him up saying “brah” and “pump that iron, arm bitch.”