Is ain't supposed to written as ain't?

Answer 1

It is not a proper word, but traditionally when it is used, it is a contraction for am not. Contractions use an apostrophe.

Example:

I am not going into that dark cave.

I ain't going into that dark cave.

In writing, it should only be used as a slang. For instance, it would help add traits to a character in a novel. However, it should never be used in formal or business writing.

Answer 2

Yes, "ain't" is a colloquial contraction commonly used in informal speech to mean "am not," "is not," "are not," "has not," or "have not." However, it is considered nonstandard English and should be avoided in formal writing.