Chemical symbol, Ni; atomic weight, 58. A metal closely related to cobalt, with which it almost always occur, a hard malleable ductile silvery metallic element that is resistant to corrosion; used in alloys; occurs in pentlandite and smaltite and garnierite and millerite, an alloy of nickel, copper, and zinc; -- usually called german silver; called also argentan, transitive verb_ To coat with nickel, To plate with nickel