manganese: Meaning and Definition of

man•ga•nese

1. a hard, brittle, grayish-white, metallic element, an oxide of which, MnOis a valuable oxidizing agent: used chiefly as an alloying agent in steel to give it toughness. Symbol: Mn; at. wt.: 54.938; at. no.: 25; sp. gr.: 7.2 at 20°C.