Meaning

noun a hard malleable ductile silvery metallic element that is resistant to corrosion; used in alloys; occurs in pentlandite and smaltite and garnierite and millerite

noun a United States coin worth one twentieth of a dollar

noun five dollars worth of a drug

originBorrowed 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.

Etymology from Wiktionary, CC BY-SA 3.0