from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Slang A stupid person; a dolt.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Derogatory term for a fool or idiot. Usually used as an insult when angry.
from The Century Dictionary and Cyclopedia
- n. A heavy, stupid fellow.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a stupid person; these words are used to express a low opinion of someone's intelligence
Probably alteration of lump1 + head.(American Heritage® Dictionary of the English Language, Fourth Edition)