To have been rendered less of a man, or been made to feel much less of a man through humiliation. This term is most often used to describe a male douchebag who has been pussywhipped by his woman.
The fact that lame Ed has chosen to neglect his friends and be home before midnight on a Friday night is proof that he has allowed himself to become completely emasculated by his girlfriend.
One who's life partner of the fairer sex earns a significantly greater level of income.
Gossiper 1: "JK Criffo is emasculated."
Gossiper 2: "*laughs* YEAH, he gets rogered by his wife with the 12 inch black latex strap-on!"