hydral,a.Bot.|ˈhaɪdrəl| [f.Gr. ὕδωρ, ὑδρ-, water + -al1.] Epithet of Lindley's alliance of Endogens containing Hydrocharidaceæ and kindred orders of aquatic plants. 1866Treas.Bot. 775 Naiadaceæ, a natural order..belonging to Lindley's hydral alliance of Endogens, consisting of plants living in fresh or salt water.