The definition of a Oxford comma is a punctuation mark used before "and" or "or" in a list of three more items.
An example of the use of the Oxford comma is the final comma in a list (after the word "nurse") written by a student when he said was "interested in a career as a teacher, a nurse, or a scientist."
A serial comma.
Origin of oxford-comma
- From Oxford University Press, where such usage of the comma is the house style