Chiefly South Midland and Southern U.S.
(used in direct address to two or more persons, or to one person who represents a family, organization, etc.):
You-all come back now, hear? Tell your mother it's time you-all came to visit us.
a US, esp Southern, word for you, used esp when addressing more than one person
Collins English Dictionary - Complete & Unabridged 10th Edition
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