n. Faithfulness within a group of sexual partners, particularly to the other members of a polygamous relationship.
2010
It's been my experience that when language changes, causes often succeed. … Turley uses the term "plural unions," and introduced me to a new word, "polyfidelity," being faithful to many lovers.
2010
Though common descriptors used for monogamy don’t easily apply to polyamory, there is a recognizable spectrum of how open these partnerships may be. On the closed end, you might have a couple in a primary relationship who will then have one or more secondary relationships that are structured to accommodate the primary one. There’s also polyfidelity, in which three or more people are exclusive with one another.
1978 (earliest)
Registration for four-day conference at Kerista Village, Utopian Egalitarian Community. Topics to include polyfidelity, culture sculpture, neotrbalism, and gestalt o'rama.