The Collaborative International Dictionary of English v.0.48:

Perspiration \Per`spi*ra"tion\, n. [Cf. F. perspiration.]
   1. The act or process of perspiring.
      [1913 Webster]

   2. That which is excreted through the skin; sweat.
      [1913 Webster]

   Note: A man of average weight throws off through the skin
         during 24 hours about 18 ounces of water, 300 grains of
         solid matter, and 400 grains of carbonic acid gas.
         Ordinarily, this constant exhalation is not apparent,
         and the excretion is then termed insensible
         perspiration.
         [1913 Webster]

WordNet (r) 3.0 (2006):

perspiration
    n 1: salty fluid secreted by sweat glands; "sweat poured off his
         brow" [syn: perspiration, sweat, sudor]
    2: the process of the sweat glands of the skin secreting a salty
       fluid; "perspiration is a homeostatic process" [syn:
       perspiration, sweating, diaphoresis, sudation,
       hidrosis]

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "perspiration":
   BO, beaded brow, beads of sweat, body odor, cold sweat, dampness,
   diaphoresis, exudate, exudation, honest sweat, lather,
   perspiration odor, streams of sweat, sudor, sudoresis, sweat,
   sweating, swelter, water, wetness