A plane figure with seven straight sides and angles.
- ‘They wore dark blue and red armor, and had a gold heptagon tattooed over their elongated green faces.’
- ‘Construct a heptagon, given the seven points that are the midpoints of its sides.’
- ‘High above us, the great heptagon of the Winter sky: Capella, Aldebaran, Rigel, Sirius, Procyon, Pollux, and Castor (with Saturn nearby) - with Betelgeuse in the center and the Milky Way cascading through, just to the left of Orion.’
- ‘A heptagon whose sides have length 2 is too large to fit tightly around a circle with radius 1.’
- ‘In this case, all of the points lying along a line through this circle's center and perpendicular to the plane of the heptagon are equidistant from the polygon's vertices.’
- ‘The book promptly answered his question: A heptagon has seven sides.’
Late 16th century: from Greek heptagonon, neuter (used as a noun) of heptagonos seven-angled.