The Collaborative International Dictionary of English v.0.48:

Adulterate \A*dul"ter*ate\, v. t. [imp. & p. p. Adulterated;
   p. pr. & vb. n. Adulterating.] [L. adulteratus, p. p. of
   adulterare, fr. adulter adulterer, prob. fr. ad + alter
   other, properly one who approaches another on account of
   unlawful love. Cf. Advoutry.]
   [1913 Webster]
   1. To defile by adultery. [Obs.] --Milton.
      [1913 Webster]

   2. To corrupt, debase, or make impure by an admixture of a
      foreign or a baser substance; as, to adulterate food,
      drink, drugs, coin, etc.
      [1913 Webster]

            The present war has . . . adulterated our tongue
            with strange words.                   --Spectator.
      [1913 Webster]

   Syn: To corrupt; defile; debase; contaminate; vitiate;
        sophisticate.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

adulterated \adulterated\ adj.
   1. having been made impure by addition of inferior
      ingredients; -- said of substances or foods

   Note: used ususally of articles of commerce, dulted with less
         costly materials so as to enhance profit; -- usually
         imlying that the dilution is surreptitious and
         unethical

   Syn: adulterate, debased
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

adulterated
    adj 1: mixed with impurities [syn: adulterate, adulterated,
           debased]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "adulterated":
   airy, attenuate, attenuated, blemished, cut, damaged, defective,
   deficient, dilute, diluted, erroneous, ethereal, fallible, faulty,
   fine, flimsy, found wanting, gaseous, immature, impaired,
   imperfect, imprecise, impure, inaccurate, inadequate, incomplete,
   inexact, insubstantial, lacking, makeshift, mediocre, mixed,
   not perfect, off, partial, patchy, rare, rarefied, reduced, short,
   sketchy, slight, subtile, subtle, tenuous, thin, thinned,
   thinned-out, uncompact, uncompressed, undeveloped, uneven,
   unfinished, unperfected, unsound, unsubstantial, unthorough,
   vaporous, wanting, watered, watered-down, windy