puzzling perplexing impenetrable mysterious mystifying inexplicable unfathomable incomprehensible obscure bewildering enigmatic confusing cryptic abstruse unclear unaccountable strange opaque wildering weird unexplained bemusing elusive complicated complex difficult intricate involved inscrutable convoluted knotty hard ambiguous labyrinthine thorny arcane tricky unintelligible elaborate insoluble recondite deep tangled confounding esoteric problematical involute troublesome odd tortuous paradoxical problematic equivocal oracular unexplainable unknowable enigmatical ticklish indecipherable sophisticated peculiar mystic occult sibylline unsolvable elliptical dark byzantine murky involuted secret awkward tough elliptic spiny labyrinthian daedal entangled hidden taxing fathomless vague nebulous confused baroque complicate fuliginous hairy profound serpentine unsolved insolvable delicate sticky indescribable prickly inextricable sensitive contradictory inconsistent