The Collaborative International Dictionary of English v.0.48:

Garfish \Gar"fish`\, n. [See Gar, n.] (Zool.)
   (a) A European marine fish (Belone vulgaris); -- called
       also gar, gerrick, greenback, greenbone,
       gorebill, hornfish, longnose, mackerel guide,
       sea needle, and sea pike.
   (b) One of several species of similar fishes of the genus
       Tylosurus, of which one species (T. marinus) is
       common on the Atlantic coast. T. Caribb[ae]us, a very
       large species, and T. crassus, are more southern; --
       called also needlefish. Many of the common names of the
       European garfish are also applied to the American
       species.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Greenback \Green"back"\, n.
   One of the legal tender notes of the United States; a note of
   paper currency of the United States; -- first issued in 1862,
   and having the devices on the back printed with green ink, to
   prevent alterations and counterfeits.
   [1913 Webster]

WordNet (r) 3.0 (2006):

greenback
    n 1: a piece of paper money (especially one issued by a central
         bank); "he peeled off five one-thousand-zloty notes" [syn:
         bill, note, government note, bank bill, banker's
         bill, bank note, banknote, Federal Reserve note,
         greenback]

U.S. Gazetteer Places (2000):

Greenback, TN -- U.S. city in Tennessee
   Population (2000):    954
   Housing Units (2000): 416
   Land area (2000):     7.081947 sq. miles (18.342157 sq. km)
   Water area (2000):    0.127051 sq. miles (0.329060 sq. km)
   Total area (2000):    7.208998 sq. miles (18.671217 sq. km)
   FIPS code:            30880
   Located within:       Tennessee (TN), FIPS 47
   Location:             35.655751 N, 84.164898 W
   ZIP Codes (1990):     37742
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Greenback, TN
    Greenback