A man who lets his wife or girlfriend have sex with other men. Often the man lets her do whatever she wants and treat him like shit.
(Short version of cuckold)
A man who is desperate for acceptance, approval, and affection from women. This desperation has led to the compromise of his beliefs and values, the desecration of his dignity and self-worth, and his inability to stand up for himself and what he deserves as a human being, eg. loyalty, fidelity, and honesty in a romantic relationship.
I know John's always wanted a girlfriend but since him and Mary started dating he's become a cuck. She spends all of his money and flirts openly with other men. I can tell it bothers him but he's so afraid of losing her that he doesn't say anything.
Originally a term to describe a man who loves watching his wife fuck other another man, or multiple men at the same time, while he just watches and masturbates. Nowadays it's basically a term for a pussy who let's women walk all over him..aka a DOORMAT
Jim: Last week my wife wouldn't let be drink a beer. I only wanted a single pint
Biff: Dave, you're such a cuck. Stand up for yourself for fuck sake