Source : Webster's Revised Unabridged Dictionary (1913)

Silica \Sil"i*ca\, n. [NL., from L. silex, silics, a flint.]
   (Chem.)
   Silicon dioxide, SiO?. It constitutes ordinary quartz (also
   opal and tridymite), and is artifically prepared as a very
   fine, white, tasteless, inodorous powder.

Source : WordNet®

silica
     n : a white or colorless vitreous insoluble solid (SiO2);
         various forms occur widely in the earth's crust as quartz
         or cristobalite or tridymite or lechartelierite [syn: {silicon
         oxide}, {silicon dioxide}]