- Digon (Wikipedia)
In geometry, a bigon, digon, or a 2-gon, is a polygon with two sides (edges) and two vertices. Its construction is degenerate in a Euclidean plane because either the two sides would coincide or one or both would have to be curved; however, it can be easily visualised in elliptic space. It may also be viewed as a representation of a graph with two vertices, see “Generalized polygon”.
- A minusagon is a value that when added to a polygon, removes one or more sides from that polygon. Compare with a plusagon, which adds a side. Some mathematicians argue that minusagons and plusagons are the same type of object. Others argue they don’t exist.