IDIOMS are according to the Merriam-Webster dictionary:
1 a: the language peculiar to a people or to a district, community, or class : dialect b: the syntactical, grammatical, or structural form peculiar to a language
2: an expression in the usage of a language that is peculiar to itself either grammatically (as no, it wasn't me) or in having a meaning that cannot be derived from the conjoined meanings of its elements (as Monday week for “the Monday a week after next Monday”)
3: a style or form of artistic expression that is characteristic of an individual, a period or movement, or a medium or instrument <the modern jazz idiom>; broadly : manner, style <a new culinary idiom>
updated 29.4.2008