before vowels crypt-, word-forming element meaning "secret" or "hidden, not evident or obvious," used in forming English words at least since 1760 (crypto-Calvinianism), from Latinized form of Greek kryptos "hidden, concealed, secret" (see crypt; the Greek combining form was krypho-).

In 19c. often of secret religious faith; from 1870s in scientific words; since c. 1945 typically of hidden political loyalties. Crypto-fascist is attested from 1937; crypto-communist from 1946. Hence, as an abstracted noun, crypto "person who conceals a political adherence" (1946).