A woman who has sexual intercourse which concludes with ejaculation on her back side. Usually as a sign of disrespect and/or due to cosmetic defects on the front side of one's body (i.e. the face or breasts), cumbacker is often used as an ironic pun as the male will rarely come back once he is spent.
Sally knew she was a cumbacker when Johnny ejaculated onto her back and left without saying good-bye.
by Kalen Williams February 05, 2005