Dodecagon

Part of speech: noun

Definitions

1. A geometric figure defined by twelve straight edges and corners exists in various mathematical contexts
2. this specific shape is classified as having twelve equal-length sides and angles
3. A polygon that has exactly twelve straight sides and twelve vertices

Etymology: The dodecagon is about as transparent as English compounds get: it is built from two Greek pieces, "dōdeka," meaning twelve, and "-gōnon," meaning angle or corner, which gave us the "-gon" ending shared by pentagon, hexagon and octagon. The "dodeca-" element works the same way, appearing in words such as dodecahedron, a solid with twelve faces. So a dodecagon is literally a "twelve-cornered" shape, and the name tells you what to count: twelve angles, and therefore twelve sides. Because the parts are so plainly Greek and so openly descriptive, the word is a technical coinage rather than an ancient one. The Greeks who studied polygons used numeral-based names like these, and English simply borrowed the pattern, building names by attaching a number to "-gon" as geometry needed them. Other members of the family, such as heptagon or nonagon, follow exactly the same logic.