The Collaborative International Dictionary of English v.0.48:

Nickel \Nick"el\, n. [G., fr. Sw. nickel, abbrev. from Sw.
   kopparnickel copper-nickel, a name given in derision, as it
   was thought to be a base ore of copper. The origin of the
   second part of the word is uncertain. Cf. Kupfer-nickel,
   Copper-nickel.]
   1. (Chem.) A bright silver-white metallic element of atomic
      number 28. It is of the iron group, and is hard,
      malleable, and ductile. It occurs combined with sulphur in
      millerite, with arsenic in the mineral niccolite, and with
      arsenic and sulphur in nickel glance. Symbol Ni. Atomic
      weight 58.70.
      [1913 Webster]

   Note: On account of its permanence in air and inertness to
         oxidation, it is used in the smaller coins, for plating
         iron, brass, etc., for chemical apparatus, and in
         certain alloys, as german silver. It is magnetic, and
         is very frequently accompanied by cobalt, both being
         found in meteoric iron.
         [1913 Webster]

   2. A small coin made of or containing nickel; esp., a
      five-cent piece. [Colloq. U.S.]
      [1913 Webster]

   Nickel silver, an alloy of nickel, copper, and zinc; --
      usually called german silver; called also argentan.
      [1913 Webster]

WordNet (r) 3.0 (2006):

nickel
    n 1: a hard malleable ductile silvery metallic element that is
         resistant to corrosion; used in alloys; occurs in
         pentlandite and smaltite and garnierite and millerite [syn:
         nickel, Ni, atomic number 28]
    2: a United States coin worth one twentieth of a dollar
    3: five dollars worth of a drug; "a nickel bag of drugs"; "a
       nickel deck of heroin" [syn: nickel, nickel note]
    v 1: plate with nickel; "nickel the plate"

Moby Thesaurus II by Grady Ward, 1.0:

92 Moby Thesaurus words for "nickel":
   C, C-note, G, G-note, aureate, bar, brass, brassy, brazen, bronze,
   bronzy, buck, bullion, cartwheel, cent, century, coin gold,
   coin silver, copper, coppery, cupreous, cuprous, dime, dollar,
   dollar bill, ferrous, ferruginous, fifty cents, fin, fish,
   five cents, five hundred dollars, five-dollar bill,
   five-hundred-dollar bill, five-spot, fiver, four bits, frogskin,
   gilt, gold, gold nugget, gold-filled, gold-plated, golden, grand,
   half G, half a C, half dollar, half grand, hundred-dollar bill,
   ingot, iron, iron man, ironlike, lead, leaden, mercurial,
   mercurous, mill, nickelic, nickeline, nugget, penny, pewter,
   pewtery, precious metals, quarter, quicksilver, red cent, sawbuck,
   silver, silver dollar, silver-plated, silvery, skin, smacker,
   steel, steely, ten cents, ten-spot, tenner, thousand dollars,
   thousand-dollar bill, tin, tinny, twenty-dollar bill,
   twenty-five cents, two bits, two-dollar bill, two-spot, yard,
   yellow stuff



The Elements (07Nov00):

nickel
Symbol: Ni
Atomic number: 28
Atomic weight: 58.71
Malleable ductile silvery metallic transition element. Discovered by
A.F.
Cronstedt in 1751.