A colloquialism is a word, phrase or other form used in language. Dictionaries often display colloquial words and phrases with the abbreviation colloq. as an identifier. Colloquial language, colloquial dialect, or informal language is a variety of language commonly employed in conversation or other communication in informal situations. The word colloquial by its etymology originally referred to speech as distinguished from writing, but colloquial register is fundamentally about the degree of informality or casualness rather than the medium, and some usage commentators thus prefer the term casualism.