A regional or social variety of a language distinguished by pronunciation, grammar, or vocabulary, especially a variety of speech differing from the standard literary language or speech pattern of the culture in which it exists: Cockney is a dialect of English. A variety of language that with other varieties constitutes a single language of which no single variety is standard: the dialects of Ancient Greek. The language peculiar to the members of a group, especially in an occupation; jargon: the dialect of science. The manner or style of expressing oneself in language or the arts. A language considered as part of a larger family of languages or a linguistic branch. Not in scientific use: Spanish and French are Romance dialects.