Synonyms for Half-wit:

adj.

unintellectual (adjective)
unintellectual, foolish, imbecilic, moronic, idiotic, cretinous, unintelligent, defective.

n.

joker, maniac, numpty, clown, dumb blond. ding-dong (noun)
meathead.
dunce (noun)
bonehead, nincompoop, lame-brain.
fool (noun)
clod, moron, ignoramus, simpleton, nitwit, cretin, dumbbell, chuckle-head, knuckle-head, bonehead, crackpot, dullard, bungler, clown, dunce, dolt, lame-brain, imbecile, loon, dummy, meathead, dimwit, fool, blockhead, nincompoop.
half-wit (noun)
clod, simpleton, blockhead, dullard, dimwit, imbecile, ignoramus, dolt, doofus, dunce, nitwit, dumbbell, fool, changeling, moron, cretin.
nitwit (noun)
dummy.
stupid person (noun)
dunce.

Other synonyms:

Other relevant words:
doofus, changeling.