- a hard, silvery-white, ductile and malleable metallic element, allied to iron and cobalt, not readily oxidized: used chiefly in alloys, in electroplating, and as a catalyst in organic synthesis. Symbol: Ni; atomic weight: 58.71; atomic number: 28; specific gravity: 8.9 at 20°C.
- a cupronickel coin of the U.S., the 20th part of a dollar, equal to five cents.
- a nickel coin of Canada, the 20th part of a dollar, equal to five cents.
- to cover or coat with nickel; nickel-plate.
- costing or worth five dollars: a nickel bag of heroin.
- a malleable ductile silvery-white metallic element that is strong and corrosion-resistant, occurring principally in pentlandite and niccolite: used in alloys, esp in toughening steel, in electroplating, and as a catalyst in organic synthesis. Symbol: Ni; atomic no: 28; atomic wt: 58.6934; valency: 0, 1, 2, or 3; relative density: 8.902; melting pt: 1455°C; boiling pt: 2914°C
- a US and Canadian coin and monetary unit worth five cents
- to plate with nickel
