idiom

Short definition from Wiktionary

Noun

1. 1
   A manner of speaking, a mode of expression peculiar to a language, language family, or group of people.
2. 2
   A manner of speaking, a mode of expression peculiar to a language, language family, or group of people: A programming construct or phraseology that is characteristic of the language.
3. 3
   A language or language variety; specifically, a restricted dialect used in a given historical period, context etc.
4. 4
   An established phrasal expression whose meaning may not be deducible from the literal meanings of its component words.
5. 5
   An artistic style (for example, in art, architecture, or music); an instance of such a style.