Meaning of undecagon in English:

undecagon

Pronunciation /ʌnˈdɛkəɡ(ə)n/

noun

another term for hendecagon
‘These various polygon shapes consist of, but are not limited to, triangles, squares, pentagons, hexagons, heptagons, octagons, nonagons, decagons, undecagons, and dodecagons.’
  • ‘How many diagonals are needed to divide a heptagon, a nonagon, and an undecagon into triangles?’

Origin

Early 18th century formed irregularly from Latin undecim ‘eleven’, on the pattern of decagon.