Nonmongamy Definition: In contrast to monogamy, nonmonogamy is a relationship structure in which any or all aspects of sexual, romantic, and emotional entanglement are not limited to be between two people.

Added context from Hanna & Lizzie:

The power of defining this term as simply the negative of monogamy is that nonmonogamy can be expressed and practiced in a myriad of ways. Simply not limiting a romantic or sexual relationship to two humans does not even require there to be more than two humans! One can be nonmonogamous and single, as practiced by many who identify as solo