Pēn’ta-gon, n.

n. [Gr. πεντάγωνον, from πέντε, five, and γωνία, angle; Lat. pentagonium, It. & Sp. pentagono, Fr. pentagone.] (Geom.) A plane figure having five angles, and, consequently, five sides.

Regular pentagon, a pentagon in which the angles are all equal, and likewise the sides all equal.