nickel
n. C / Un. a silver-colored coin used in the United States and Canada that is worth five cents. It is also the name of a hard, silver-white metal used to make other metals stronger.
n. a silver-white, metallic element used in alloys; also, a five-cent coin in the United States and Canada. When referring to the metal, it is typically uncountable; when referring to the coin, it is countable.
I found a nickel on the sidewalk today.
The cashier gave me two dimes and a nickel back as change for my purchase.
Industrial manufacturers often plate steel with nickel to provide a protective layer that resists corrosion and improves the overall durability of the component.
Borrowed from German Nickel, first used in a text by the Swedish mineralogist Axel F. Cronstedt as an abbreviation of Kupfernickel (“a mineral containing copper and nickel”), from Kupfer (“copper”) + Nickel (“insignificant person, goblin”), originally nickname of Nikolaus (“Nicholas”), due to the deceptive silver colour of the relatively valueless ore. Compare cobalt as related to kobolds.
Uncountable when referring to the chemical element; countable when referring to the specific five-cent coin.