CRYPTOLECT

n.

A secret language.

"Unlike modern slang the ancient cant approaches the notion of a...'cryptolect,' as described by Ian Hancock. Altered by time, it retains a degree of currency in the British Isles and North America among Travelers, a traditionally itinerant people including the Roma (Gypsies) and other groups."

— J. E. Lighter, Random House Historical Dictionary of American Slang, Volume I

antilanguage

camouflanguage

ebonics

Greenspeak

manual babbling

Menglish

pubilect

slanguist

Spinnish

stego

Language (General)