Synonyms for Dimwit:

n.

DUMBO, thickhead, numskull, ability, chump, dummkopf. a stupid person (noun)
dunce, dullard, bonehead, imbecile, dolt, numskull, fool, blockhead, moron, simpleton, ignoramus.
dimwit (noun)
half-wit, doofus, nitwit.
fool (noun)
nincompoop, bungler, simpleton, half-wit, dolt, dumbbell, loon, ignoramus, crackpot, imbecile, blockhead, nitwit, dummy, moron, bonehead, meathead, cretin, knuckle-head, dullard, dunce, chuckle-head, lame-brain, clod, fool.
ignoramus (noun)
buffoon, birdbrain, scatterbrain.
person (noun)
half-wit, doofus, nitwit.
stupid person (noun)
dunce, clod, dolt, dummy.
thickhead (noun)
dummkopf.

Other synonyms:

dummkopf, chump, thickhead, DUMBO. numskull. Other relevant words:
dummkopf, doofus, chump, numskull, ability, DUMBO, thickhead.