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The chief constituent of sand, hence of glass. SYN: silicic anhydride, silicon dioxide. [Mod. L. fr. L. silex (silic-), flint]
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sil·i·ca 'sil-i-kə n the dioxide of silicon SiO2 that is used as an ingredient of simethicone and that occurs naturally in crystalline, amorphous, and impure forms (as in quartz, opal, and sand respectively) called also silicon dioxide
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sil·i·ca (silґĭ-kə) [L. silex flint] SiO2, silicon dioxide or silicic anhydride, occurring in nature as agate, sand, amethyst, chalcedony, cristobalite, flint, quartz, and tridymite. It is one of the major constituents of dental porcelain and a common filler in resin composites; in granular form it serves as a dental abrasive and polishing agent. See also silicosis.Medical dictionary. 2011.