Fluosilicic \Flu`o*si*lic"ic\, a. [Fluo- + silicic: cf. F. fluosilicique.] (Chem.) Composed of, or derived from, silicon and fluorine. {Fluosilicic acid}, a double fluoride of hydrogen and silicon, {H2F6Si}, obtained in solution in water as a sour fuming liquid, and regarded as the type of the fluosilicates; -- called also {silicofluoric acid}, and {hydrofluosilicic acid}.