Delta Triad
A form of PolyAmory where three people are intimately involved, each one with both of the others. This grouping can have other PolyAmory facets as well. EG: PolyFidelity, PolyDating, etc.
Jan and Dave and Susan are in a Poly relationship. Jan and Dave are intimate, Jan and Susan are intimate, and Dave is intimate with Susan as well as Jan.