(uncountable) A silvery elemental metal with an atomic number of 28 and symbol Ni.

(US, Canada, countable) A coin worth 5 cents.

(US, slang, by extension) Five dollars.

(US, slang, by extension) Five hundred dollars.

(US, slang, sometimes the nickel or the hot nickel) Interstate 5, a highway that runs along the west coast of the United States.

(slang) A playing card with the rank of five

(US, slang) A five-year prison sentence.

(American football) A defensive formation with five defensive backs, one of whom is a nickelback, instead of the more common four.

(UK, World War II) An airborne propaganda leaflet.

(transitive) To plate with nickel.

(UK, World War II) To distribute airborne leaflet propaganda.

(US, idiomatic, somewhat dated) Synonym of cheap: Low price and/or low value.