In sociolinguistics, a variety, also known as a lect or an isolect, is a specific form of a language or language cluster. This may include languages, dialects, registers, styles, or other forms of language, as well as a standard variety. The use of the word “variety” to refer to the different forms avoids the use of the term language, which many people associate only with the standard language, and the term dialect, which is often associated with non-standard varieties thought of as less prestigious or “correct” than the standard. Linguists speak of both standard and non-standard (vernacular) varieties. “Lect” avoids the problem in ambiguous cases of deciding whether two varieties are distinct languages or dialects of a single language.
Variation at the level of the lexicon, such as slang and argot, is often considered in relation to particular styles or levels of formality (also called registers), but such uses are sometimes discussed as varieties as well.