Amn't is a contraction of "am not" occurring in some dialects of English, mainly Scottish English and Hiberno-English. The contraction is formed in the same way as "aren't" from "are not" and "isn't" from "is not". It has been suggested that the reason why "amn't" is not as widespread as other contractions is that English tends to dislike the nasal consonants /m/ and /n/ together. In Scottish English, amn't is generally used only when inverted as a question (i.e. "amn't I?"); in Hiberno-English it is also used in statements ("I amn't") and sometimes as a double negative ("amn't I not?"):
Standard English uses "I'm not" and "am I not?" or "aren't I?" in place of "I amn't" and "amn't I?". Other dialects use "I ain't" and "ain't I?". In Scots, the equivalent would be "Ah amny", or "Ah'm no".