The Collaborative International Dictionary of English v.0.48:

Exhalation \Ex`ha*la"tion\, n. [L. exhalatio: cf. F. exhalaison,
   exhalation.]
   1. The act or process of exhaling, or sending forth in the
      form of steam or vapor; evaporation.
      [1913 Webster]

   2. That which is exhaled, or which rises in the form of
      vapor, fume, or steam; effluvium; emanation; as,
      exhalations from the earth or flowers, decaying matter,
      etc.
      [1913 Webster]

            Ye mists and exhalations, that now rise
            From hill or steaming lake.           --Milton.
      [1913 Webster]

   3. A bright phenomenon; a meteor. [archaic]
      [1913 Webster +PJC]

            I shall fall
            Like a bright exhalation in the evening. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

exhalation
    n 1: exhaled breath [syn: halitus, exhalation]
    2: the act of expelling air from the lungs [syn: exhalation,
       expiration, breathing out]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "exhalation":
   air, breath, effluvium, emanation, emission, evaporation, exhaust,
   expiration, fog, fume, gas, mist, puff, respiration, steam,
   suspiration, vapor, whiff