Entry 1 sense Webster, 1913 Hydrofluosilicate · Hy·dro·flu·o·sil·i·cate · IPA 01 n. A salt of hydrofluosilic acid; a silicofluoride. See Silicofluoride. 1. A salt of hydrofluosilic acid; a silicofluoride. See Silicofluoride.(Chem.) See: Silicofluoride