silica

n [U] compound of silicon occurring as quartz or flint, and in sandstone and other rocks 硅石; 二氧化硅.

signatory, signature, signature tune (also theme tune), signet, signet ring, significance, significant, significantly, signification, signify, signor, signpost, Sikh, silage, silence, silencer, silent, silent film, silently, silhouette, silicate, silicon, silicon chip, silicone, silicosis, silk, silk-screen printing, silken, silkiness, silkworm, silky, sill, sillabub, silliness, silly, silly (also silly-billy), silo, silt, silty, silvan (also sylvan),