A monogon is a two-dimensional polygon with a single edge. In Euclidean space, it is degenerate, with the edge being of zero length and the shape having no area, but it can exist as a tiling of the circle with the edge taking up the whole circle.
All monogons are regular, because they only have one vertex and one edge.
Structure and Sections
|Regular ||Rectified ||Truncated ||Monogon||Monogon||Digon|