opaque (adj.)

• abstruse
• ambiguous
• amorphous
• arcane
• asinine
• backward
• baffling
• black
• blind
• blockish
• blurred
• blurry
• bovine
• cloddish
• clouded
• cloudy
• crass
• cryptic
• dark
• dense
• dim
• doltish
• dull
• dumb
• duncical
• duncish
• elusive
• enigmatic
• equivocal
• fat
• foggy
• fuzzy
• gross
• hazy
• impenetrable
• impermeable
• indefinite
• indeterminate
• indistinct
• lumpish
• misty
• muddy
• murky
• mysterious
• mystifying
• nebulous
• oafish
• obscure
• obtuse
• perplexing
• puzzling
• recondite
• roiled
• roily
• shadowy
• shapeless
• slow
• smoky
• sottish
• stolid
• stupid
• tenebrous
• thick
• thickheaded
• transcendent
• turbid
• uncertain
• unclear
• unfathomable
• unintelligent
• unintelligible
• vague
• wrongheaded