The whole connected network of people linked by relationships — a 'molecule' of partners and metamours.
The word is a blend of "poly" (as in polyamory) and "molecule," and that second half is the whole point. Draw your relationships as dots and lines — people as atoms, connections as bonds — and the diagram looks like something out of a chemistry textbook. That is a polycule: the map, not just the couple. A three-person V (one person dating two others who aren't dating each other) is a polycule. So is a sprawling web of a dozen people across three cities.
The common misconception is that a polycule means everyone is sleeping with everyone. It isn't. The defining feature is connection, not saturation — you can belong to the same polycule as someone you've never touched, simply because you both date the same person. That person-in-the-middle has a name too (your metamour), and a lot of polycule life is really about those sideways relationships, not the direct ones.
Where it actually shows up: people use "polycule" the way monogamous folks say "my relationship" — as the unit they're describing. "Our polycule does the holidays together." It's descriptive, not a status you apply for; the shape shifts as people pair off, drift, or connect. And it's worth being honest that the tidy molecule diagram flatters the reality — real ones involve scheduling, jealousy, and the occasional breakup that reshapes the whole structure.