PRIVATE LANGUAGE. LANGUAGE used for private or in-group purposes; a particular language or variety of a language used for such purposes, such as adolescent SLANG, criminal ARGOT, and technical JARGON. A private language that is intended to be opaque to all or most outsiders is known technically as a cryptolect (‘hidden dialect’). Such languages are difficult to study because they often change rapidly and investigators have difficulty gaining admission to the groups that use them. The travellers or travelling people of Europe and North America, a group that includes but is not limited to Gypsies or Romanies, use various cants and forms of ROMANI as a language of the roads, to mark their ethnic identity and exclude outsiders. The linguist Ian Hancock, of Romany descent, has reported on these cryptolects: for example, in ‘Romani and Angloromani’ (in P. Trudgill (ed.), Language in the British Isles, 1984).

In California, a more localized private language called Boontling (also Boonville Lingo) has been used since the 1880s around Boonville in the upper Anderson Valley of Mendocino County. Used as the secret language of sheep-shearing crews and baseball teams, and to keep adult discussions secret from children, Boontling was most effective in separating locals from outsiders, who could not easily fathom its altered pronunciations, abbreviations, and personal associations. Among its evasive usages were: burlap (sometimes shortened to burl) to have sexual intercourse, dreef coitus interruptus, keeboarp premature ejaculation, moldunes breasts, nonch harpins objectionable talk, especially about sexual matters.

Perhaps the most common form of private usage in English occurs in families. Parents often coin private usages, such as nicknames and child-orientated EUPHEMISMS for bodily parts and functions, and adopt expressions used by their children when they were learning to speak. Twins are also sometimes credited with developing a private language that only they can understand. Family usages are often sustained for years without outsiders knowing much or anything about them. Perhaps the most opaque and isolated form of private language is that of schizophrenics. Although private language is widespread, no definitive study of the subject as a whole currently exists. See BACK SLANG, CANT, DOUBLE TALK, POLARI, RHYMING SLANG.