cassideous,a.Bot.|kæˈsɪdiːəs| [f. L. cassidem helmet + -eous.] Helmet-shaped, helmet-like. 1835Lindley Introd.Bot. (1848) I. 335 If the corolla is very irregular with one petal very large and helmet-shaped it is sometimes called cassideous.1880Gray Bot.Text-bk.