adulterator

from WordNet (r) 3.0 (2006)

adulterator
    n 1: any substance that lessens the purity or effectiveness of a
         substance; "it is necessary to remove the adulterants
         before use" [syn: {adulterant}, {adulterator}]
    2: a changer who lessens the purity or effectiveness of a
       substance

from The Collaborative International Dictionary of English v.0.48

Adulterator \A*dul"ter*a`tor\, n. [L.]
   One who adulterates or corrupts. [R.] --Cudworth.
   [1913 Webster]