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

Inside is a lineup of ingredients sourced straight from Icelandic waters—microalgae to stimulate collagen levels, silica to improve moisture retention, and seawater to protect the skin barrier. —Emily Orofino, Vogue, 19 Feb. 2026

However, these voxels required high-purity silica glasses. —IEEE Spectrum, 18 Feb. 2026

At its core is volcanic-ash bentonite clay, an ingredient rich in minerals including calcium, magnesium, and silica. —Justin Fenner, Robb Report, 16 Feb. 2026

While the Blue Lagoon—its waters milky with mineral-rich silica—remains the most famous, drawing up to a million visitors a year, smaller, less touristy lagoons have been appearing across the country, from Sky Lagoon on Kársnes Harbour near Reykjavik to Forest Lagoon in Iceland’s far north. —Rick Jordan, Travel + Leisure, 8 Feb. 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