dialect, variety of a language used by a group of speakers within a particular speech community. Every individual speaks a variety of his language, termed an idiolect. Dialects are groups of idiolects with a common core of similarities in pronunciation, grammar, and vocabulary. Dialects exist as a continuum in which adjacent dialects are mutually intelligible, yet with increasing isolation between noncontiguous dialects, differences may accumulate to the point of mutual unintelligibility. For example, in the Dutch-German speech community there is a continuous area of intelligibility from Flanders to Schleswig and to Styria, but with Flemish and Styrian dialects mutually unintelligible. Adjacent dialects usually differ more in pronunciation than in grammar or vocabulary. When a dialect is spoken by a large group of speakers of a language, it often acquires prestige, which leads to the development of a standard language. Some countries have an official standard, such as that promoted by the French Academy. The first linguistic dialectology focused on historical dialects, written texts serving as the basis for establishing the dialects of a language through the methods of comparative linguistics.
The methods of modern linguistic geography began in late 19th-century Europe with the use of informants rather than texts, and resulted in the first linguistic atlases of France, by Jules Gilliéron, and of Germany, by Georg Wenker. Those techniques were refined in the United States in the preparation of the Linguistic Atlas of the United States (Hans Kurath et al., ed.) and its derivative works. In recent years linguists have become increasingly interested in social dialects, such as the languages of social groups within an urban population and the languages of specific occupations (farmers, dockworkers, coal miners, government workers) or lifestyles (beatniks, drug users, teenagers, feminists). In the United States much work has been done in the area of black English, the common dialect of many African Americans. See also slang.
See H. Orton and E. Dieth, ed., Survey of English Dialects (1962–70); H. B. Allen and G. N. Underwood, Readings in American Dialectology (1971); R. H. Bentley and S. D. Crawford, ed., Black Language Reader (1973); H. Kurath, Studies in Area Linguistics (1973); P. Trudgill, Dialects in Contact (1986); C. M. Carver, American Regional Dialects (1987).