Used in
polyamorous contexts, a person's lover's other lover. A partner's partner, the person your sweetie is banging, etc. Unlike mistress or
paramour, "metamore" connotes that neither relationship is
clandestine.
There was a lot of tension in my relationship with Joe, so I had dinner and talked through it with a metamour, Casey. They were able to bring a lot of perspective, and things with Joe really
smoothed out. The next week we made an
Eiffel Tower.
Now that I'm dating Ludacris, I have
metamours in every area code.