What does the contraction ain't mean? Is it appropriate to use it in formal settings?
From the Merriam-Webster:
Main Entry: ain't
Etymology: contraction of are not
Quoting @nohat :
The common bit of schoolyard wisdom that “ain’t ain’t in the dictionary, so ain’t ain’t a word” turns out to be untrue. Every online dictionary that I’ve ever looked in contained an entry for ain’t.
It is a colloquial word, informal, so probably shouldn't be used in formal settings,
unless you are a politican:)