A silvery-white metal, the chemical element of atomic number 28, used in alloys and for plating. The coin was made of nickel, giving it a shiny appearance.
A five-cent coin in the United States and Canada. He found a nickel on the sidewalk and picked it up.
A monetary unit equal to five cents. The candy bar cost a nickel back in the day.
American football: a defensive formation that employs five defensive backs; a nickel defense. On third and long, the coach sent in a nickel to counter the opponent's passing attack.