Linguistics. a variety of a language that is distinguished from other varieties of the same language by features of phonology, grammar, and vocabulary, and by its use by a group of speakers who are set off from others geographically or socially.
a provincial, rural, or socially distinct variety of a language that differs from the standard language, especially when considered as substandard.
a special variety of a language:
The literary dialect is usually taken as the standard language.
a language considered as one of a group that have a common ancestor:
Persian, Latin, and English are Indo-European dialects.
1577, from M.Fr. dialecte, from L. dialectus "local language, way of speaking, conversation," from Gk. dialektos, from dialegesthai "converse with each other," from dia- "across, between" + legein "speak" (see lecture).