decagonal

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decagon

dec·a·gon

D0066100 (dĕk′ə-gŏn′)n. A polygon with ten sides and ten angles.
[Medieval Latin decagōnum, from Greek dekagōnon, from neuter of dekagōnos, having ten angles : deka, ten; see dekm̥ in Indo-European roots + -gōnos, angled; see -gon.]
de·cag′o·nal (dĭ-kăg′ə-nəl) adj.de·cag′o·nal·ly adv.