Definition of heptagon noun from the Oxford Advanced Learner's Dictionary

 

heptagon

 noun
noun
BrE BrE//ˈheptəɡən//
 
; NAmE NAmE//ˈheptəɡɑːn//
 
(geometry)
 
jump to other results
a flat shape with seven straight sides and seven angles Word Origin late 16th cent.: from Greek heptagonon, neuter (used as a noun) of heptagonos ‘seven-angled’.
See the Oxford Advanced American Dictionary entry: heptagon