Real Dictionary

manganese
uncountable noun: Manganese is a greyish-white metal that is used in making steel.

manganese in American English
a grayish-white, metallic chemical element, usually hard and brittle, which rusts like iron but is not magnetic: it is used in the manufacture of alloys of iron, aluminum, and copper: symbol, Mn; at. no., 25
noun: a hard, brittle, grayish-white, metallic element, an oxide of which, MnO2 (manganese dioxide), is a valuable oxidizing agent: used chiefly as an alloying agent in steel to give it toughness; at. wt.: 54.938; at. no.: 25; sp. gr.: 7.2 at 20°C

manganese in British English
noun: a brittle greyish-white metallic element that exists in four allotropic forms, occurring principally in pyrolusite and rhodonite: used in making steel and ferromagnetic alloys. Symbol: Mn; atomic no: 25; atomic wt: 54.93805; valency: 1, 2, 3, 4, 6, or 7;