Below is a list of terms used by nonmonogamous, especially polyamorous, people.
compersion: a feeling of happiness when your partner experiences pleasure with another partner; the opposite of jealousy
hierarchy: a dating structure in which one pairing is considered of greater importance or rank than others (see also primary partner, secondary partner)
metamour: your partner's other partner, e.g. your wife's boyfriend
NRE: new relationship energy—the period early in a dating relationship when everything feels exciting and wonderful
parrots: often associated with poly ("Polly"). Seen as a picture rather than spoken or written as a term. Can be a way for poly people to identify themselves and each other without being "out"
primary partner, primary: a partner considered more important or a higher rank than others. Some people have multiple primaries. Sometimes refers to a partner that looks more like a traditional partner (i.e. the person you live with, have children with, are married to, etc.) (see also secondary partner)
pod: a group of people connected through shared relationships and friendship (see also polycule, tribe)
polyamory: the practice of engaging in multiple relationships at the same time. Typically associated with an emphasis on loving more than one person (poly—many, amory—love) rather than having many sexual partners
polycule: a group of people connected through shared relationships and friendship (see also pod, tribe)
polyfamily: a group of people who consider each other family. Often they live together and raise children together
polyfidelity: a relationship containing more than two partners, but in which none of the individuals is allowed to date anyone outside the relationship
quad: a group of four people who are all in relationships with each other
relationship anarchy (RA): a relationship style that places heavy emphasis on not making rules to control the behavior of your partners and not being controlled by the rules of others
secondary partner, secondary: a partner considered less important or a lower rank than others (see also primary partner)
solo poly: the practice of intentionally staying away from primary partnerships, especially eschewing living with partners, getting married, sharing finances, and having children with primary partners
triad: a relationship made up of three people who all date each other
tribe: a group of people connected through shared relationships and friendship (see also pod, polycule)
V: a relationship in which two metamours (the arms of the V) share the same partner (the point of the V) (see also W)
W: a relationship between five people, made up of two Vs with a connecting partner in the middle (e.g. Sam dates Mallory who dates Bill who dates Jessica who dates Chris) (see also V)
Is something wrong or missing? Please let me know in the comments!