Adjectives

(a)ill-defined, unclearpoorly stated or described“he confuses the reader with ill-defined terms and concepts”
(a)unclearnot clear to the mind“the law itself was unclear on that point”, “the reason for their actions is unclear to this day”
(s)indecipherable, unclear, undecipherable, unreadablenot easily deciphered“indecipherable handwriting”