Synonyms for Half-wit:

adj.

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

n.

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

Other synonyms:

Other relevant words:
changeling, doofus.