throuple

noun

throu·​ple ˈthrə-pəl 

plural throuples

: a consensual romantic relationship involving three people

My girlfriend's ex-husband has moved into a flat with two women. They're all sleeping in one bed and openly telling the world they're a proud throuple.

—Jane O'Gorman

On their first date, he revealed he was polyamorous and hoped she wouldn't mind. He'd been part of a throuple that had just given their third the heave-ho.

—Taffy Brodesser-Akner

… TV shows and movies that depict throuples, polycules and other permutations of open relationships …

—Alexandra Alter

Word History

Etymology

thr(ee) + (c)ouple entry 1

First Known Use

2004, in the meaning defined above