The Collaborative International Dictionary
orthosilicic acid
Silicic \Si*lic"ic\, a. [L. silex, silicis, a flint: cf. F. silicique.] (Chem.) Pertaining to, derived from, or resembling, silica; specifically, designating compounds of silicon; as, silicic acid.
Silicic acid (Chem.), an amorphous gelatinous substance, Si(HO)4, very unstable and easily dried to silica, but forming many stable salts; -- called also orthosilicic acid or normal silicic acid.
Wiktionary
orthosilicic acid
n. (context chemistry English) The hypothetical compound Si(OH)4; it is only known as the orthosilicate salts or esters.