A contraction for are not and am not; also used for is not. [Colloq. or illiterate speech]. See An't.
Source: Webster's dictionaryAll music is folk music. I ain't never heard a horse sing a song. Louis Armstrong
Truth is like the sun. You can shut it out for a time, but it ain't going away. Elvis Presley
One man alone can be pretty dumb sometimes, but for real bona fide stupidity, there ain't nothin' can beat teamwork. Edward Abbey
Ain't over till the fat lady sings. English Proverb
Don't mend what ain't broken. English Proverb
Common sense ain't common. English Proverb