Idiom - the language, dialect, or style of speaking peculiar to a people or the constructions or expressions of one language whose structure is not matched in another language. Idioms often possess a meaning other than their grammatical or logical ones and cannot be directly translated into another language. It also is used to describe something peculiar to an individual.
The word comes from the Greek idioma, meaning “a peculiarity in language” which was derived from idio, and omai, together meaning “make one’s own.”
In the original Greek, the word was used to mean either a private citizen or something belonging to a private citizen, hence, personal.
Some examples in English are “no wonder,” “better late than never,” “to lead by the nose,” and “spick and span.”