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

In future winters, Maler recommends applying silica and calcium spray to strengthen and protect the tree. —Lois K. Solomon, Sun Sentinel, 31 Jan. 2026

That's because this material creates an unusual amount of lung-damaging silica dust when it gets cut or polished, far more than natural granite or marble. —Nell Greenfieldboyce, NPR, 14 Jan. 2026

Today, only one small mine extracting the mineral anorthosite, which is useful for its aluminum and silica, is running. —Paul Bierman, Fortune, 14 Jan. 2026

But if the geological plumbing is clogged, perhaps by silica minerals or rock debris, the pressure can build until the water explodes, vaporizing into steam and shooting boiling water, mud, rocks, and other debris into the air. —Owen Clarke, Outside, 23 Dec. 2025

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