1560s, from French heptagon, from Greek heptagonon, from hepta "seven" (see septi-) + gōnia "angle, corner" (from PIE root *genu- (1) "knee; angle"). Related: Heptagonal.
Entries linking to heptagon
septi-
before vowels sept-, word-forming element meaning "seven," from Latin septem (see seven). A parallel formation to septem-.
*genu- 1
Proto-Indo-European root meaning "knee; angle."
It forms all or part of: agonic; decagon; diagonal; geniculate; genuflect; genuflection; -gon; goniometer; heptagon; hexagon; knee; kneel; octagon; orthogonal; pentagon; polygon; trigonometry.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit janu, Avestan znum, Hittite genu "knee;" Greek gony "knee," gōnia "corner, angle;" Latin genu "knee;" Old English cneo, cneow "knee."