| a white, tasteless substance, magnesium oxide, MgO, used in medicine as an antacid and laxative. |

| a city in W Turkey, near the Aegean: Roman defeat of Antiochus the Great 190 b.c. 72,276. |
magnesia mag·ne·sia (māg-nē'zhə, -shə)
n.
Magnesium oxide.