Source : Webster's Revised Unabridged Dictionary (1913)

Pollution \Pol*lu"tion\, n. [L. pollutio: cf. F. pollution.]
   1. The act of polluting, or the state of being polluted (in
      any sense of the verb); defilement; uncleanness; impurity.

   2. (Med.) The emission of semen, or sperm, at other times
      than in sexual intercourse. --Dunglison.

Source : WordNet®

pollution
     n 1: undesirable state of the natural environment being
          contaminated with harmful substances as a consequence of
          human activities
     2: the state of being polluted [syn: {befoulment}, {defilement}]
     3: the act of contaminating or polluting; including (either
        intentionally or accidentally) unwanted substances or
        factors [syn: {contamination}] [ant: {decontamination}]