The construction of the word to me implies that "you" is singular, whereas "y'all" is plural.
To a football team: "Y'all are going to play a great game." To a tennis player: "You are going to play a great game."
However, I hear southerners address me personally as Y'all quite often.
What's the correct usage?
Aside: Comments that y'all is improper are not helpful.
From what I understand, most dialects work as you describe: you = singular and y'all = plural.
There is some controversy over whether some dialects have extended this further, such that y'all = singular and "all y'all" = plural.
Here is a discussion over at Language Log, where they say that there is a lot of disagreement about this. I think the overall sense from this article is that people have anecdotes and random quotes where people use y'all as a singular, but no person from the South who attests that "yes, this is what I do."
And here is a followup discussion. Here there is a similar type of disconnect between anecdote and speaker intuition. There seems to be mention that in Oklahoma, y'all can be used for singular and plural, which, if true, might be fueling a false conclusion about "all y'all" being the plural of singular y'all.
There is a lot more in there, and it is worth a read for anyone interested, but the last thing I wanted to mention was this hypothesis at the end of that page:
Thomas Nunnally (1994) has offered a second hypothesis for the emergence of yall as a singular. He suggests that it may well be expanding to fill the role of a polite singular, just as you did several centuries ago. He points out that many of the citations of yall-singular show the form occurring at the edges of discourse-in greetings, partings, and so forth. The following citation, provided to us by Robin Sabino (1994), certainly fulfills this function. Sabino overheard an African-American waitress in an Opelika, Alabama, restaurant say to a customer eating alone, "How are you-all's grits?"
All of this may seem strange, but if you look at the origin of you itself, the same thing happened: it used to be that thou/thee was 2nd person singular and ye/you was 2nd person plural, but as we know, plural you became the 2nd person pronoun for singular and plural (in Standard English, at least). So these kinds of shifts are possible.
Note: This has been extensively edited in light of some research I found over at Language Log.
This is the way I always explain it. You is singular. "Are you going to lunch after church?"meaning you yourself, singular. Y'all is plural. "Are y'all going to lunch after church? meaning is any of your group going. All y'all is what I call plural inclusive. "Are all y'all going to lunch after church?"meaning is every single last one of your group going. Important details when you need a head count to reserve a table.
"Y'all" was originally coined as a contraction of "you all" and thus was originally used as the second-person plural pronoun, comparable to "ustedes" in Spanish and "vous" in French. It fills a void in the English language as compared to Latin languages and even German, which all have at least one second-person plural pronoun. Classically, "you" has had both the singular and plural roles, and if a distinction had to be made, the phrase "all of you" or "you all" is correct for the plural. The dual meaning is likely French in origin; the pronoun "vous" in French, in addition to being the general second-person plural, is also used as a polite second-person singular. It's an artifact of culture, particularly high culture, similar to the "royal 'we'". The term carries into English through a combination of English's beginnings in French and also through off-and-on English obsessions with French culture throughout history.
Its usage as a singular, if one has to try to make the shoe fit, may come from a mingling of English-derived Deep South and French-influenced Creole/Cajun cultures. "Y'all" may have come into common use through Creole adaptation of the term to replace both of the uses of the French counterpart "vous".
Now, IMO that's stuffing the shoe on the wrong foot. Vernacular speech, no matter the language, is full of "common-use" grammar errors. As a native Okie and naturalized Texan, IMO the use of "y'all" as anything other than a contraction of "you all" is more of the same.
