When a man watches his wife or girlfriend have sex with another man.

A cuckold is a man who gets turned on his watching his wife fuck other men. Cuckolding occurs when a married woman fucks another man with her husband's full knowledge and consent. She does it because it makes him hard as a rock and often because he is inadequate in bed.

cuckold: a man married to an unfaithful wife.

so, cuckolding is whne the wife is doing the cheating.

A man who willingly encourages his wife to sleep with other people because it brings him pleasure. Cuckolds exist on a spectrum between two extremes. One on end is the masochistic cuckold who enjoys humiliations, degradation, and other demeaning activities at the hands of his wife and her lover. The alpha cuckold lies at the opposite end of the spectrum and does not enjoy any form of humiliation and often has a direct say in who his wife sleeps with and when.

Jerry Falwell, Jr.

A man who finds arousement in watching his girlfriend/wife having sex with another man.

A man who enjoys watching his wife commit adultery or be unfaithful with other men.