The Collaborative International Dictionary of English v.0.48:

Discriminate \Dis*crim"i*nate\, v. t. [imp. & p. p.
   Discriminated; p. pr. & vb. n. Discriminating.]
   To set apart as being different; to mark as different; to
   separate from another by discerning differences; to
   distinguish. --Cowper.
   [1913 Webster]

         To discriminate the goats from the sheep. --Barrow.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Discriminating \Dis*crim"i*na`ting\, a.
   1. Marking a difference; distinguishing. --
      Dis*crim"i*na`ting*ly, adv.
      [1913 Webster]

            And finds with keen discriminating sight,
            Black's not so black; -- nor white so very white.
                                                  --Canning.
      [1913 Webster]

   2. making careful or fine distinctions, especially as to
      quality or accuracy; as, a discriminating observer.

   Syn: discerning, perspicacious. [PJC]

   3. having a refined taste or excellent judgment; as, a
      discriminating taste.
      [PJC]

WordNet (r) 3.0 (2006):

discriminating
    adj 1: showing or indicating careful judgment and discernment
           especially in matters of taste; "the discriminating eye
           of the connoisseur" [ant: indiscriminating,
           undiscriminating]
    2: having or demonstrating ability to recognize or draw fine
       distinctions; "an acute observer of politics and
       politicians"; "incisive comments"; "icy knifelike reasoning";
       "as sharp and incisive as the stroke of a fang"; "penetrating
       insight"; "frequent penetrative observations" [syn: acute,
       discriminating, incisive, keen, knifelike,
       penetrating, penetrative, piercing, sharp]

Moby Thesaurus II by Grady Ward, 1.0:

90 Moby Thesaurus words for "discriminating":
   accurate, adoptive, appointive, appreciative, careful, censorious,
   characteristic, characterizing, choicy, choosing, choosy,
   circumspect, civilized, conscientious, considerate, constituent,
   contrastive, critical, cultivated, cultured, dainty, delicate,
   diacritical, diagnostic, differencing, differential,
   differentiative, discerning, discreet, discriminate,
   discriminative, distinctive, distinguishing, eclectic, elective,
   electoral, elegant, enlightened, exact, exacting, fastidious, fine,
   fussy, graceful, gracile, gracious, idiosyncratic, individualizing,
   individuating, judgmatic, judicial, judicious, keen, meticulous,
   nice, particular, peculiar, perceptive, perfectionistic,
   personalizing, picky, polished, politic, precise, precisianistic,
   priggish, provident, prudent, prudential, prudish, punctilious,
   puristic, puritanic, refined, reflecting, reflective, scrupulous,
   select, selecting, selective, sensitive, separative, sophisticated,
   strict, subtle, tactful, thoughtful, well-advised, well-judged,
   wise