Meaning of series comma

se'ries com"ma

Pronunciation: [key]
  1. 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
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.