One who engages in the process of systematically dating an obscene amount people in short span of time. This definition encompasses but is not limited to internet dating, bar dating, long distance flirtations, phone service dating, blind dating, expiration dating, match making, one night stands, friends with benefits, and personal ad surfing. Can be considered a politically correct alternative to word "player" both with and without a negative connotation.
You do not want to date my roommate, that guy is such a serial dater.
Good luck getting anything meaningful out of her, she's too much into serial dating.