Boeotian, abstruse, adiaphanous, ambiguous, amorphous, amphibological, arcane, asinine, backward, baffling, becloud, beef-brained, beef-witted, black, blind, blockish, blurred, blurry, bovine, chumpish, clear as mud, cloddish, cloud, clouded, cloudy, cowish, crass, cryptic, dark, darken, dense, dim, doltish, dull, dull-witted, dullard, dumb, duncical, duncish, dunderheaded, elusive, enigmatic, equivocal, fat, foggy, fuzzy, gross, grumly, hazy, impenetrable, impermeable, impervious to light, indefinite, indeterminate, indistinct, ineducable, intransparent, klutzy, lumpish, misty, muddy, murky, mysterious, mystifying, nebulous, nubilous, oafish, obfuscated, obscure, obscured, obtuse, perplexing, puzzling, recondite, roiled, roily, shadowy, shapeless, slow, smoky, sottish, stolid, stupid, tenebrous, thick, thickheaded, transcendent, turbid, uncertain, unclear, unfathomable, unintelligent, unintelligible, unplain, unteachable, vague, wrongheaded