Source : Webster's Revised Unabridged Dictionary (1913)

Contaminate \Con*tam"i*nate\ (k[o^]n*t[a^]m"[i^]*n[=a]t), v. t.
   [imp. & p. p. {Contaminated}; p. pr. & vb. n.
   {Contaminating}.] [L. contaminatus, p. p. of contaminare to
   bring into contact, to contaminate, fr. contamen contagion,
   for contagmen; con- + root of tangere to touch. See
   {Contact}.]
   To soil, stain, or corrupt by contact; to tarnish; to sully;
   to taint; to pollute; to defile.

         Shall we now Contaminate our figures with base bribes?
                                                  --Shak.

         I would neither have simplicity imposed upon, nor
         virtue contaminated.                     --Goldsmith.

   Syn: To pollute; defile; sully; taint; tarnish; soil; stain;
        corrupt.

Contaminate \Con*tam"i*nate\ (-n[asl]t), a.
   Contaminated; defiled; polluted; tainted. ``Contaminate
   drink.'' --Daniel.

Source : WordNet®

contaminate
     v 1: make impure; "The industrial wastes polluted the lake" [syn:
           {pollute}, {foul}]
     2: make radioactive by adding radioactive material; "Don't
        drink the water--it's contaminated" [ant: {decontaminate}]