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

At this infrared wavelength, the interaction of the light with the silica glass is disappearingly small. —John Ballato, The Conversation, 24 Mar. 2026

Blue Lagoon Skin Science’s gentle foaming cleanser, packed with microalgae, Icelandic seawater, and silica, provides both antioxidant protection and hydration. —Conçetta Ciarlo, Vogue, 19 Mar. 2026

Gandhi believes high-silica countertops should be banned, since even tiny lapses in protective measures put workers at risk of silicosis, and natural and low-silica alternatives are available. —Ethan Baron, Mercury News, 16 Mar. 2026

Workers, physicians, and plaintiffs' attorneys counter that a material composed almost entirely of crystalline silica may be impossible to handle safely at scale. —Dr. Céline Gounder, CBS News, 12 Mar. 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