ain’t
The contraction of am not, and its wider stand-in for isn’t, aren’t, and hasn’t.
Do not use ain’t in standard English. It is at home in dialogue, in quoted speech, and in a deliberate informal voice. It is not a polished substitute for isn’t, aren’t, I’m not, or hasn’t.
Examples
UseI am not ready.
Use“I ain’t going,” he said.
AvoidThe data ain’t complete.
Ain’t has a long history and is fully alive in many spoken varieties. That does not make it the default.