heptagon
(ˈhɛptəgən)
[ad. Gr. ἑπτάγωνον, neut. of ἑπτάγωνος seven-cornered. Cf. F. heptagone (1542 in Hatz.-Darm.).]
1. Geom. A plane figure having seven angles and seven sides.
| 1570 Billingsley Euclid i. xxxii. 42 In an heptagon, from one angle may be drawne lines to foure opposite angles. 1660 Barrow Euclid iv. xi. Schol., The side of a Heptagone. 1885 C. Leudesdorf Cremona's Proj. Geom. 187 Suppose it is required to inscribe in the conic a heptagon. |
b. Fortif. A place strengthened with seven bastions for its defence.
| 1706 in Phillips (ed. Kersey). |
2. attrib. or adj. = heptagonal.
| 1775 R. Putnam in Romans Florida 335 It [a fort] was built of a heptagon figure, with one side fronting the river. |