High Quality Content by WIKIPEDIA articles! Ain`t is a colloquialism and contraction for "am not", "is not", "are not", "has not", and "have not" in the common English language vernacular. In some dialects ain`t is also used as a contraction of "do not", "does not", and "did not". The usage of ain`t is a perennial subject of controversy in English. Widely used by many people, and found in most dictionaries, its use is often considered by prescriptionists to be informal, nonstandard, or improper.