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).
word-forming element indicating "branch of knowledge, science," now the usual form of -logy. Originally used c. 1800 in nonce formations (commonsensology, etc.), it gained legitimacy by influence of the proper formation in geology, mythology, etc., where the -o- is a stem vowel in the previous element.
The second element is prop[erly] -logy (-logue, etc.), the -o- belonging to the preceding element; but the accent makes the apparent element in E[nglish] to be -ology, which is hence often used as an independent word. [Century Dictionary]
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Definitions of cryptology from WordNet
the science of analyzing and deciphering codes and ciphers and cryptograms;