Dimethicone

Part of speech: noun

Definitions

1. A silicone-based polymer used in lotions, creams and hair products to form a smooth protective film on the skin
2. A synthetic silicone compound added to cosmetics and medical ointments to soften the skin and repel water
3. An oily siloxane polymer widely used in personal care products and barrier creams for its slippery, water-repellent qualities

Etymology: Dimethicone is a silicone polymer, and its name is a chemist's construction rather than an ancient or folk word. It is built from "di-", meaning two, and "methyl", the name of the CH3 group, plus the "-icone" ending that chemists adopted for silicone compounds, which were named by analogy with ketones such as acetone. Silicones were first made in the early twentieth century, when the English chemist Frederic Stanley Kipping studied organosilicon compounds in the 1900s and 1910s, so the name dates from that period rather than from classical antiquity. The chemistry explains the name. Each repeating unit in the polymer has a silicon atom carrying two methyl groups, so "dimethyl" describes the substituents on each silicon, and the "-icone" ending reflects the silicon-oxygen backbone. Dimethicone's most common use is in cosmetics and skincare, where its slippery, water-repellent feel makes it a familiar ingredient in creams, shampoos and hair products.

Synonyms: polydimethylsiloxane