An anti-language is a language created and used by an anti-society. An anti-society is a small, separate community intentionally created within a larger society as an alternative to or resistance of it. For example, Adam Podgorecki studied one anti-society composed of Polish prisoners; Bhaktiprasad Mallik of Sanskrit College studied another composed of criminals in Calcutta. Anti-languages are developed by these societies as a means to prevent outsiders from understanding their communication, and as a manner of establishing a subculture that meets the needs of their alternative social structure. Anti-languages differ from slang and jargon in that they are used solely among ostracized or rebellious social groups including prisoners, criminals, homosexuals, and teenagers. Anti-languages use the same basic vocabulary and grammar as their native language in an unorthodox fashion. For example, anti-languages borrow words from other languages, create unconventional compounds, or utilize new suffixes for existing words. Anti-languages may also change words using metathesis, back formation (e.g. apple to elppa), or by substituting their consonants. Therefore, anti-languages are distinct and unique, and are not simply dialects of existing languages.
The concept of anti-languages was first defined and studied by the linguist Michael Alexander Kirkwood Halliday, who used the term to describe the lingua franca of an anti-society. In his essay "Anti-Language," M.A.K. Halliday synthesized the research of Thomas Harman, Adam Podgorecki, and Bhaktiprasad Mallik to explore anti-languages and the connection between verbal communication and the maintenance of social structure. For this reason, the study of anti-languages is both a study of sociology and linguistics. M.A.K.'s findings can be compiled as a list of nine criteria that a language must meet to be considered an anti-language.
Ulti is a language studied and documented by Bhaktiprasad Mallik in his book Languages of the Underworld of West Bengal. Ulti is an anti-language derived from Bengali and used by criminals and affiliates. The Ulti word kodān, meaning 'shop,' is derived from rearranging the letters in the Bengali word dokān, which also means 'shop'. On the other hand, the Bengali word thām, meaning 'pillar', means 'a girl's thigh' in Ulti.
Anti-languages are sometimes created by authors and used by characters in novels. These anti-languages do not have complete lexicons, cannot be observed in use for linguistic description, and therefore cannot be studied in the same way that a language that is actually spoken by an existing anti-society would. However, they are still used in the study of anti-languages. Roger Fowler's "Anti-Languages in Fiction" analyzes Anthony Burgess's A Clockwork Orange and William S. Burroughs' Naked Lunch to redefine the nature of the anti-language and to describe its ideological purpose.
A Clockwork Orange is a popular example of a novel in which the main character is a teenage boy that speaks an anti-language called Nadsat. This language is often referred to as an argot, but it has been argued to be an anti-language because of the social structure that it maintains through the existence of the social class of the droogs.