Metamour

A metamour is your partner's partner. In polyamory and other forms of consensual non-monogamy, if you and another person are both intimately involved with the same person, the two of you are metamours to each other, even though you are not dating one another. The word blends the Greek prefix "meta" (beyond) with the French "amour" (love), roughly "the love beyond." It is often shortened to "meta." Metamour relationships range widely: some people are close friends with their metamours, some are cordial, and some rarely interact. The term gives polyamorous families a clear way to name a connection that older relationship vocabulary never had a word for.