Unisilicate \U`ni*sil"i*cate\, n. [Uni- + silicate.] (Min.) A salt of orthosilicic acid, {H4SiO4}; -- so called because the ratio of the oxygen atoms united to the basic metals and silicon respectively is 1:1; for example, {Mg2SiO4} or 2{MgO.SiO2}. [1913 Webster]