a comma used after the next-to-last item in a series of three or more items when the next-to-last and last items are separated by a conjunction. In the series A, B, C, or D, the comma after C is the series comma. Also called serial comma .
SERIES COMMA
Meaning of SERIES COMMA in English
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012