A colloquialism is a word, phrase, or paralanguage that is employed in conversational or informal language but not in formal speech or formal writing. Dictionaries often display colloquial words and phrases with the abbreviation colloq. as an identifier. Colloquialisms are sometimes referred to collectively as "colloquial language".
Read more about Colloquialism: Examples, Distinction From Slang, Distinction From Jargon, Distinction From Dialect