V (vee)
Also: V-shaped polycule
A polycule shape in which one person is partnered with two others who are not partnered with each other.
A V is the simplest non-trivial polycule shape. Three people are involved. The central person — the hinge — is partnered with each of the other two. Those other two are not partnered with each other; they are metamours. The diagram drawn on a napkin looks exactly like a letter V.
Most polycules either start as a V or contain a V as a substructure. A couple opening their relationship who each take an outside partner often forms two adjacent V shapes (the original couple is each at the hinge of their own V). A solo polyamorous person with two partners who do not know each other socially is the hinge of a V. The structure is everywhere because it is the natural shape that emerges from one person having more than one partner.
What distinguishes a V from a triad is the absence of the third edge. A triad has all three people partnered with each other; a V has only two of the three edges. The two arrangements ask very different things of the people in them. The triad is a three-way relationship; the V is two relationships that share a person.
The healthy V is one where the two metamours are explicit with each other about the shape and where the hinge does not try to merge the two relationships into something they are not. Vees can persist for decades without the metamours ever becoming close — and that is fine as long as the structure was named and chosen rather than allowed to drift into resentment.