late 14c., in alchemy, "main ingredient of the philosopher's stone," from M.L. magnesia, from Gk. (he) Magnesia (lithos) "the lodestone," lit. "(the) Magnesian (stone)," from Magnesia, region in Thessaly. Perhaps manganese is meant. Connection with magnet is obscure. Main modern sense of "magnesium oxide" (1755) is perhaps an independent formation from L. magnes carneus "flesh-magnet" (c.1550), so called because it adheres strongly to the lips.
(māg-nē'zhə) A white powder with a very high melting point. It is used to make heat-resistant materials, electrical insulators, cements, fertilizer, and plastics. It is also used in medicine as an antacid and laxative. Chemical formula:MgO.