Everybody uses it, even people who say they don’t get caught using it from time to time. I understand that there isn’t a longer version of “ain’t”, like “aren’t” means “are not”.
But why can’t we just go ahead and add it just like it is to the dictionary? I think the word is used more than the proper grammatical terms. Hell, the word exists because people use it, so why not?
Who makes decisions to add words to dictionaries? Who makes decisions on what words are in the proper grammar categories?
It is.
I just looked in three dictionaries, and “ain’t” was in all three.
Generally, with the better dictionaries, the decisions are based on what words are actually being used, and not on what dictioonary-makers think ought to be used. However, they might give a warning like “non-standard” against words like “ain’t” – which just means that a lot of people think that “ain’t” ain’t a good word to use in formal contexts, even if a lot of people use it colloquially.
What **don’t ask ** said. I think you’d have a hard time finding an english dictionary in which ain’t ain’t present. Here’s one on-line example: Merriam-Webster . Also, this is probably the wrong forum for your inquiry.
Although in this thread there are several posts where “ain’t ain"t” ain’t present.
Well, i stand corrected. I’ve always been told “ain’t” ain’t a word.
It’s the contraction for “am not,” as in “I am not going to the store.”
I think it’s a perfectly cromulent word that fulfills a need not found in the present “standard” English language. There’s a lot of words out there that fill a need but ain’t considered proper. For instance, English has a real need for a second-person plural pronoun, yet the words that people come up with to fulfill this necessary function that exists in all other European languages (y’all, yinz) are seen as hickish. Likewise, we really need a gender-neutral pronoun. “They” fulfills this concept and it is easy to tell whether you mean singular or plural they from context (“every student should put their books away”), but traditional grammarians think it’s wrong.
It’s a damn shame, I tells ya. English should be allowed to grow and change. There are lots of words and concepts we need to have in the language and “ain’t” fulfills one of them perfectly. I think the only reason it’s not considered a proper word is that it originated among the lower classes. Why shouldn’t there be a contraction for “are not”?
Of course not. That’s because ain’t ‘“ain’t ain**”**t" ain’t’ ain’t right ain’t “ain’t ain’t” is.
Now you’ve got it. Now, why ain’t ain’t spelled amn’t? Splain that.
Well, first, there is a contraction for “are not”. It’s “aren’t”
I think part of the reason that “ain’t” isn’t accepted more is because of the contraction “I’m”, which is more useful. Since, as you said, “ain’t” is a contraction of “am not”, and since the verb form “am” is only used with "I’, “I ain’t going to the store” and “I’m not going to the store” aere interchangeable.
And, since the contraction “I’m” can be used a lot more often, it became the default.
Interesting Etymonline entry - the word orignally was ‘correct’, and then became supposed slang or colloqialism. ain't | Search Online Etymology Dictionary
The “problem” with “ain’t” is that it is “properly” a contraction for “Am not”, and for that, it’s pretty useless (you lose one letter, and you have the same number of keystrokes).
However, some hundred years ago (and I could be off on the dating), “ain’t” started being a contraction for quite a few things- “He ain’t”, "We ain’t, “They ain’t”. Personally, I think this would have been great. But it bothered the presciptionists, who they started a campaign to make “ain’t” “no such word”. Today, it makes you sound somewhat like a hick, due to this campaign.
There is: “aren’t.” Like you said, ain’t is a contaction for “am not.” 
The weird thing is “ain’t” is in the dictionary, but “gullible” isn’t.
Cite?
Gadarene, why don’t you look it up and prove him wrong?
Well, there isn’t an official government body set up to guard and pontificate on the English language like there is with, say, French, the Oxford English Dictionary is regarded as the nearest thing to an official record of the language - it includes ‘ain’t’ in it, which in my book makes it a word, albeit a slang one.
What makes you say that English isn’t allowed to grow and change? New words are being added to the dictionary all the time. “Bling”, for example is pretty much a mainstream word now.
I think that ain’t has evloved to mean “most certainly am/is/are not”. I tend to use it that way-- ie, a stronger version of am/is/are not.
You won’t believe me, but I actually got a buddy with this. It wasn’t until he triumphanty read out about half the definition that he realized he’d been had.
You own the OED?