cryptology

The science or study of mathematical, linguistic, and other coding patterns and histories.

Meronyms: cryptography, cryptanalysis; encoding, decoding; encrypting, decrypting, decyphering

The practice of analysing encoded messages, in order to decode them.

Near-synonyms: cryptanalysis, decoding, decrypting, decyphering

Secret or enigmatical language.

But the question of speech-play causes confusion to the slang researcher because this subject borders on family slang, private lingo, secret language, cryptologies, disguised language of children and grown-ups