metamour

meta- +‎ amour (probably influenced by paramour).

• IPA^(key): /ˈmɛtəmʊə(ɹ)/, /ˈmɛtəmɔː(ɹ)/

metamour (plural metamours)

1. (uncommon) In a polyamorous relationship, one's partner's partner, with whom one is not directly involved.
   • 2000 August 11, Liz W, “When your wife loves to be at the center...!”, in alt.polyamory‎ (Usenet):

     I get it less with women who are bi and poly than with women who are monosexual and monogamous/monoamorous, but I can't put my finger on why, and there are exceptions in both directions. I get it less with metamours than with women who are unrelated, but maybe that's just because if my metamours were alien to me, there's a fair chance they'd be alien to my partners too, or conversely that I'd have been alien to the partners when they were still just potential partners, and hence we'd never become metamours in the first place.

   • 2024 January 16, Allison P. Davis, “What Does a Polycule Actually Look Like?”, in New York Magazine‎:

     […] — and in considering how jealous I would feel if Anna (or honestly any of this polycule, because yes, reader, they are all hot) were my metamour, I imagine what it would be like, how destabilizing to watch your partner grow closer and more intimate and happier with another person; […]