• cnm/enm = consensual/ethical non-monogamy
• comet/satellite = a partner one sees infrequently, often long distance, with low commitment expectations
• ✶ compersion = vicarious joy for your partner's other relationships (opposite of jealousy)
• hierarchical polyamory = in which you might have a primary and secondary partner etc
• hinge = see 'v relationship'
• metamour /ˈmɛt əˌmʊər/ (meta) = your partner's other partner(s)
• nesting partner = the partner you live with
• polycule = a group of people connected by their overlapping relationships
  • 2 people that are together, monogamous or not = dyad / couple
  • 3 people that are all in a relationship with each other = triad ﹡
  • 4 people that are all in a relationship with each other = quad
• polyfidelity / closed relationship = a polycule that is closed to new partners
• polysaturated = having as as many relationships as one can reasonably handle, without the capacity for more
• relationship anarchy = (1) a relationship ideology that rejects conventional rules about relationships (2) a type of non-hierarchical polyamorous relationship structure
• relationship escalator = the progression of a relationship, or the idea that a relationship has to 'go somewhere' (aka become increasingly commited) and can't go backwards
• solo polyamory = polyamorous person that chooses not to have a primary partner so their lives are not enmeshed with someone else. typically also does not subscribe to the idea of the relationship escalator
• unicorn = bisexual individual willing to join an existing couple (for sex or a relationship)
• v relationship = one hinge partner dating multiple people, but those do not date each other

partially picked up myself from media/books/etc, partially from r/polyamory.