Colloquialism

A colloquialism is a word that is not used in formal speech or writing. Colloquialisms are also sometimes referred to collectively as "colloquial language".[1] Colloquialisms or colloquial language is considered to be characteristic of or only appropriate for casual, ordinary, familiar, or informal conversation rather than formal speech or writing.[2] Dictionaries often mark colloquial words and phrases with the abbreviation colloq. as an identifier.