Analysis of Ain't

The contraction ain't is considered a nonstandard form of am not. It was first used extensively in the early nineteenth century in the Cockney dialect of London. In addition to am not, ain't can also mean are not, is not, have not and has not.

The word was derived from am not. The following illustrates the process:

am not --> amn't (vowel deletion)
amn't --> an't (consonant deletion)
an't --> ain't (vowel raising)

Here are examples with ain't:

I ain't seen him = I haven't seen him.
You ain't told me = You haven't told me.
I ain't sure = I'm not sure.
You ain't late = You aren't late.
He ain't well = He isn't well.

The five examples illustrate the different uses of ain't. Though the contraction isn't considered standard, it often occurs in informal speech. In writing, though, the word is far less frequent.