Also found in: Wikipedia.
(or se′rial) com′ma,
a comma placed after the next-to-last item in a series when the last item is preceded by a conjunction, as the comma after C in the series A, B, C, or D.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.