Cryptic

a.
  1. incomprehensible to those not familiar with the culture or jargon; as, the new insurance policy is written without cryptic or mysterious terms.
  2. having a secret or hidden meaning; as, cryptic symbols engraved in stone; cryptic writings.
  3. having a puzzling terseness; as, a cryptic note.
  4. not evident; unrecognized; as, a cryptic infection.
  5. written in a code or cipher; as, a cryptic message.