What does dodecagon mean?
A dodecagon is a polygon with twelve straight sides and twelve angles, making it one of the many named figures studied in classical geometry. The term derives from Greek roots meaning 'twelve' and 'angle', reflecting the precision with which mathematicians have long catalogued shapes by their number of sides. A regular dodecagon, in which all sides are equal and all interior angles measure exactly 150 degrees, is the most commonly discussed form and appears frequently in mathematics education, architectural design, and even coinage — the British twelve-sided threepence being a well-known historical example. While the word is largely confined to technical and educational contexts, it occasionally surfaces in descriptions of floor plans, tiling patterns, and decorative motifs where a twelve-fold symmetry is desired. Its three-dimensional counterpart, the dodecahedron, is a distinct solid and should not be confused with it.
nounA plane figure with twelve straight sides and twelve angles; a twelve-sided polygon.
- A plane (two-dimensional) figure bounded by twelve straight sides and having twelve interior angles.
"The fountain was set in a dodecagon of pale limestone, its twelve sides perfectly equal."
"Students learned to construct a regular dodecagon using only a compass and straightedge."
"The coin's unusual dodecagon shape made it easy to identify by touch alone."
Standard English plural, formed simply by adding -s.
"The pattern repeated dodecagons across the entire courtyard."
The humble 12-sided dodecagon tiles the plane with squares and hexagons, but its 3D cousin — the dodecahedron — so captivated the ancient Greeks that Plato assigned it to the cosmos itself.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dodecagon
The word dodecagon comes from the Greek 'dōdeka', meaning 'twelve', combined with 'gōnia', meaning 'angle' or 'corner'. It entered English via Latin during the early modern period, when European scholars were translating and systematising classical Greek geometry. Cognates from the same root include dodecahedron (a twelve-faced solid) and dodecaphonic (relating to twelve-tone music), both preserving the Greek prefix for twelve.
Related word forms
How dodecagon is actually used
Primarily a technical term used in geometry, mathematics education, and design or numismatic contexts. It is neutral in register but uncommon in everyday speech. When unspecified, 'dodecagon' may refer to any twelve-sided polygon, though 'regular dodecagon' is often specified when all sides and angles are equal.
Easily confused with dodecagon
A dodecahedron is a three-dimensional solid with twelve faces, whereas a dodecagon is a flat two-dimensional shape with twelve sides.
A decagon has ten sides, while a dodecagon has twelve — the 'dodeca-' prefix (Greek for 'twelve') makes the difference.