An idiom is a style or form of artistic expression that is characteristic of an individual, a period or a movement, or a medium or instrument. Another way to define idiom is as 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”). Idioms are often phrases we utter without even thinking about them.