bombaceous,a.Bot.|bɒmˈbeɪʃəs| [f.mod.L. bombax (f. L. bombyx silk) + -aceous.] Of or pertaining to plants of the genus Bombax, or the Silk-cotton family. 1864Bates Nat. on Amazon xvi. 139 The trees the dome-topped giants of the Leguminous and Bombaceous orders.