The Collaborative International Dictionary of English v.0.48:

Contaminate \Con*tam"i*nate\ (-n[asl]t), a.
   Contaminated; defiled; polluted; tainted. "Contaminate
   drink." --Daniel.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         Shall we now
         Contaminate our figures with base bribes? --Shak.
   [1913 Webster]

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

   Syn: To pollute; defile; sully; taint; tarnish; soil; stain;
        corrupt.
        [1913 Webster]

WordNet (r) 3.0 (2006):

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