WordNet (r) 3.0 (2006):

lowbrow
    adj 1: characteristic of a person who is not cultivated or does
           not have intellectual tastes; "lowbrow tastes" [syn:
           lowbrow, lowbrowed, uncultivated]
    n 1: a person who is uninterested in intellectual pursuits [syn:
         philistine, anti-intellectual, lowbrow]

Moby Thesaurus II by Grady Ward, 1.0:

54 Moby Thesaurus words for "lowbrow":
   Gothic, Philistine, barbarous, bookless, dabbler, deceived,
   dilettante, dunce, fool, functionally illiterate, grammarless,
   greenhorn, greeny, heathen, hoodwinked, ignoramus, ill-educated,
   illiterate, illiterati, know-nothing, led astray, middlebrow,
   misinformed, misinstructed, mistaught, no scholar, nonintellectual,
   pagan, puddinghead, rude, tenderfoot, unbooked, unbookish,
   unbooklearned, unbriefed, uncultivated, uncultured, unedified,
   uneducated, unerudite, unguided, uninstructed, unintellectual,
   unintelligentsia, unlearned, unlettered, unliterary, unread,
   unrefined, unscholarly, unschooled, unstudious, untaught,
   untutored