1830, from French hydroxide; see hydro- + oxide.

metallic alkaline element, 1807, coined by English chemist Humphry Davy from soda; so called because the element was isolated from caustic soda (sodium hydroxide). The chemical symbol Na is from natrium, alternative name for the element proposed by Berzelius from natron, a name of a type of soda.

1880, proprietary name for white suspension of magnesium hydroxide in water, taken as an antacid, invented by U.S. chemist Charles Henry Phillips. Herbal or culinary preparations more or less resembling milk had been similarly named (for example milk of almond) since late 14c.