puzzling
abstruse, ambiguous, baffling, bewildering, beyond one, enigmatic, full of surprises, hard, incomprehensible, inexplicable, involved, knotty, labyrinthine, misleading, mystifying, oracular, perplexing, unaccountable, unclear, unfathomable, clear, comprehensible, easy, evident, intelligible, lucid, manifest, obvious, patent, plain, simple, unambiguous, unequivocal, unmistakable