1. A stupid person. Did you hear that guy's ridiculous question? Geez, what a conehead.
2. Someone who is very intelligent, but with very narrow interests. Smart as he is, I doubt he'll be able to help you change your tire—he's a real conehead.
conehead
1. n. a fool; an oaf. You can be pretty much of a conehead yourself sometimes, you know.
2. n. an intellectual; a pointy-head. They build fences around universities to keep the coneheads in.
cones
n. the breasts; female breasts. She ain’t much in the cones department.