cryptic

Having hidden (unapparent) meaning.

Mystified or of an obscure nature; not easy to perceive.

I think the Original of this conceit might be, That the Students of Nature, conſcious to her more cryptick wayes of working, reſolve many ſtrange effects into the nearer efficiency of ſecond cauſes[…]

Even the putatively innocuous whimsical shapes and designs of cakes and pastry, notably in Central Europe, retain to this day the phallic concept, the cryptic induration of the aphrodisiac function.

Involving use of a code or cipher.

Of a crossword puzzle, or a clue in such a puzzle, using, in addition to definitions, wordplay such as anagrams, homophones and hidden words to indicate solutions.

Well camouflaged; having good camouflage.

Lonomia caterpillars are extremely cryptic.

A cryptic crossword puzzle.

He settled down to the cryptic in the Independent. He loved his crossword. It kept him mentally active, just as gossip did his wife.

This writer has been solving cryptics for 40 years and can usually crack Araucaria, though it might take a couple of days.