(n.) One backward in book learning; a child or other person dull or weak in intellect; a dullard; a dolt.

Boeotian block blockhead bonehead boob booby bufflehead cabbagehead chowderhead chucklehead chump clod clodpate clodpoll cluck dabbler dilettante dimwit dodo dolt dolthead donkey dope drip duffer dullard dullhead dumb dumb cluck dumbbell dummy fool gowk greenhorn greeny ignoramus illiterate illiterati jobbernowl know-nothing lackwit lamebrain lightweight looby loon lowbrow middlebrow niais nincompoop ninny ninnyhammer nitwit no scholar noddy puddinghead put stupid tenderfoot thickwit unintelligentsia witling