Synonyms for Cryptic (same or very similar meaning)
WordNet sense 1 (of an obscure nature):
deep, inscrutable, mysterious, mystifying, cryptical
WordNet sense 2 (incapable of being explained or accounted for):
incomprehensible, inexplicable
WordNet sense 3 (having a secret or hidden meaning):
sibylline, cabalistic, kabbalistic, qabalistic
WordNet sense 4 (confined to and understandable by only an enlightened inner circle):
esoteric
WordNet sense 5 (expressing much in few words):
concise
From the ODE community, based on WordNet
add/edit