crypto-, crypt-

(Greek: hidden, secret, secrets, secret writing; by extension, applied to secret code or ciphers)

telecryptograph (s) (noun), telecryptographs (pl)
A form of printing telegraph messages that is adopted so it prints secret or private communications.
Any disease of the hair follicles.
xylocryptite (s) (noun), xylocryptites (pl)
Something that is hidden in fossil wood.

A cross reference of other word family units that are related directly, or indirectly, to: "secret, hidden, confidential, concealed": ceal-; clandesti-; myster-; occult-; orgy; stego-, stegano-.