SLANG (DEFINITIONS AND CLASSIFICATIONS)
The American Heritage Dictionary (printed version)
The nonstandard vocabulary of a given culture or subculture, consisting typically of arbitrary and often ephemeral coinages and figures of speech characterized by spontaneity and sometimes by raciness.
The American Heritage Dictionary (electronic version)
1. A kind of language occurring chiefly in casual and playful speech, made up typically of short-lived coinages and figures of speech that are deliberately used in place of standard terms for added raciness, humor, irreverence, or other effect. 2. Language peculiar to a group; argot or jargon.
Collins English Dictionary (electronic version)
1. vocabulary, idiom, etc. that is not appropriate to the standard form of a language or to formal contexts, may be restricted as to social status or distribution, and is characteristically more metaphorical and transitory than standard language
2. another word for jargon.
American English: An Introduction
General slang: is used or at least understood by most native speakers of a language; arises in part from the creative use of language by speakers of the standard; also draws on specialized slang for its words and expressions
Specialized slang: is restricted to particular groups or subcultures; often called cant or jargon; produces some words and idioms that are taken up by most speakers of the language who in turn use these with the purpose of showing differences with or explicitly denying values and norms of the mainstream
The Oxford English Dictionary
identifies three types of slang:
1. (mid-18th century) the special vocabulary used by any sets of persons of a low and disreputable character (thriving today in the vocabulary of the underworld, street gangs, drug-trafficking)
2. (soon afterwards the meaning broadened to include) the special vocabulary or phraseology of a particular calling or profession (printers’ ~, doctors’ ~)
3. (from the early years of the 19th century) any language of a highly colloquial type, considered as below the level of standard educated speech, and consisting either of new words or of current words employed in some new special sense
Today slang covers all of these areas: not all colloquial or informal vocabulary is slang, but all slang is colloquial or informal.