quinquangular
/kwɪnˈkwaŋɡjʊlə/adjective
Having five angles or corners; pentagonal.
Origin
Mid 17th century; earliest use found in William Bedwell (bap. 1563, d. 1632), Arabist and mathematician. From classical Latin quīnque five + angular. Compare post-classical Latin quinquangularis, French quinquangulaire.