The Collaborative International Dictionary of English v.0.48:

Fifty \Fif"ty\, a. [AS. f[imac]ftig; akin to OHG. finfzug,
   fimfzuc, G. f["u]nfzig, funfzig, Goth. fimftigjus. See
   Five, and Ten, and cf. Fifteen.]
   Five times ten; as, fifty men.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Fifty \Fif"ty\, n.; pl. Fifties.
   1. The sum of five tens; fifty units or objects.
      [1913 Webster]

   2. A symbol representing fifty units, as 50, or l.
      [1913 Webster]

WordNet (r) 3.0 (2006):

fifty
    adj 1: being ten more than forty [syn: fifty, 50, l]
    n 1: the cardinal number that is the product of ten and five
         [syn: fifty, 50, L]
    2: a United States bill worth 50 dollars [syn: fifty dollar
       bill, fifty]

U.S. Gazetteer Places (2000):

Fifty-Six, AR -- U.S. city in Arkansas
   Population (2000):    163
   Housing Units (2000): 87
   Land area (2000):     2.061415 sq. miles (5.339040 sq. km)
   Water area (2000):    0.003936 sq. miles (0.010194 sq. km)
   Total area (2000):    2.065351 sq. miles (5.349234 sq. km)
   FIPS code:            23680
   Located within:       Arkansas (AR), FIPS 05
   Location:             35.960474 N, 92.230072 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Fifty-Six, AR
    Fifty-Six
    Fifty, AR
    Fifty