nickel

1. A silvery elemental metal with an atomic number of 28 and symbol Ni. (uncountable)
2. A coin worth 5 cents. (US, countable)
3. Five dollars. (US, countable, slang, uncountable)
4. Five hundred dollars. (US, countable, slang, uncountable)
5. Interstate 5, a highway that runs along the West Coast of the United States. (US, countable, slang, uncountable)
6. A playing card with the rank of five. (countable, slang, uncountable)
7. A five-year prison sentence. (US, countable, slang, uncountable)
8. A defensive formation with five defensive backs, one of whom is a nickelback, instead of the more-common four. (countable, uncountable)

Plural nickels