silica

noun

sil·​i·​ca ˈsi-li-kə 

: the dioxide of silicon SiO₂ occurring in crystalline, amorphous, and impure forms (as in quartz, opal, and sand respectively)

Examples of silica in a Sentence

Recent Examples on the Web

Some of the rocks contain silica, which can form when olivine reacts with water and is particularly abundant in rocks that were once below the lake's waterline. — Samantha Mathewson, Space.com, 24 Sep. 2026

Hollidge and Eshaghpour were captivated by Frank’s use of straw, which becomes more or less lustrous depending on how hard it’s rubbed (bringing out the material’s natural silica) and can be dyed to achieve different hues. — Jill Singer, Curbed, 23 Sep. 2026

The quartz silica sand used for the protective glass is mined nearby in Spruce Pine. — Charlotte Observer, 15 Sep. 2026

Then, place the packets inside an airtight container—ideally with a silica-gel packet to absorb any lingering moisture. — Bianca Lambert, Southern Living, 9 Sep. 2026

Word History

Etymology

New Latin, from Latin silic-, silex hard stone, flint

First Known Use

circa 1801, in the meaning defined above

Phrases Containing silica

• silica gel
• vitreous silica

Rhymes for silica

• basilica

Kids Definition

silica

noun

sil·​i·​ca ˈsil-i-kə 

: a compound that consists of the dioxide of silicon and occurs in various forms (as in quartz, opal, and sand)

Medical Definition

silica

noun

sil·​i·​ca ˈsil-i-kə 

: 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