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19.
ain't is the definition of things that "ain't cool" "ain't chill" "ain't fun" etc,

anything or anyone considered unpopular is often described simply as "ain't"

instead of longer sentences,

making people sound incredibly white trash and/or stupid

also often heard as "ain't shit"
Hey man, you see george whereing those sandals?

Yeah man, he ain't.

yeah i know, he ain't shit!
by you.aint.shit November 04, 2011
 
1.
slang contraction of is not, are not, am not, do not or does not.
He ain't lazy, he just ain't got nothing to do.
by superrockstar125 February 10, 2003
 
2.
<negative third person singular> Chiefly American Colloquial Contraction

A single word that is equivalent to other words such as:
1) Am not
2) Are not
3) Is not

==> Most likely originated in the Southern States of America as it flows easily with their accent but has now been used in many places around the world.
"I aint going."
"We aint going."
"He aint going."
by Stuart Fletcher January 29, 2005
 
3.
Contraction of am not and slang contraction for anything else.
I ain't gonna watch Joe Millionare 2 because it ain't good.
by Chase November 11, 2003
 
4.
Is now in a dictionary
Teacher: Ain't is not in the dictionary

Student: It's on the urbandictionary!
by martytiptoes October 20, 2010
 
5.
Originally a non-slang word, ain't began as a contraction for "am not", as in "I ain't stupid." When people began to use it improperly as in "He ain't", which should have been "He isn't", people came to consider it improper use of language. Today, it's known to be used predominantly in the south and by uneducated people.
I ain't yo' momma.

He ain't goin' to eat those nasty baked beans.
by Pitoyable May 02, 2005
 
6.
1. a combination of the words are not.
2. a combination of the words am not.
1. You aint going.
2. I aint going.
by dixielightning July 26, 2003
 
7.
A word so easy to say and understand, English teachers don't want you using it and make you read war and peace.

Ain't= Am not
Child: I Ain't trippin nigga gimme the money.

Teacher: Page 1-500 now you illiterate fool!
by Cocker spindler January 05, 2008