noun

1. the language or dialect of a people, region, class, etc.
2. the usual way in which the words of a particular language are joined together to express thought
3. a phrase, construction, or expression that is recognized as a unit in the usage of a given language and either differs from the usual syntactic patterns or has a meaning that differs from the literal meaning of its parts taken together (Ex.: not a word did she say; she heard it straight from the horse's mouth)
4. the style of expression characteristic of an individual the idiom of Hemingway
5. a characteristic style, as in art or music

Etymology: < Fr & LL: Fr idiome < LL idioma < Gr idiōma, peculiarity, idiom < idios: see idio-