The word ain't is considered by many to be incorrect or "bad" English but it is common in the very informal speech of some people. It can be used to mean am not, are not, is not, have not, and has not.

Is Ain't correct grammar?

Ain't is a perfectly valid word, but today, ain't is considered nonstandard. At worst, it gets stigmatized for being “ignorant” or “low-class.” At best, it's considered a no-no in formal writing. Ain't wasn't always so looked down upon, though.

Where do you use Ain't in a sentence?

You ain't going to like this. I ain't seen her take the whip to you once. She says she ain't hungry.