pentăgōnĭus, a, um, adj., = πενταγώνιος and pentăgōnus, a, um, = πεντάγωνος,
quinquangular , pentagonal. — Subst.: pentăgōnĭum , i, n., a pentagon (post-class.): pentagonii ratio, Auct. de Limit. p. 257 Goes.— pentăgōnum , i, n., for pentaphyllon, App.Herb. 2.