The Collaborative International Dictionary of English v.0.48:

Distinction \Dis*tinc"tion\, n. [L. distinctio: cf. F.
   distinction.]
   1. A marking off by visible signs; separation into parts;
      division. [Obs.]
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            The distinction of tragedy into acts was not known.
                                                  --Dryden.
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   2. The act of distinguishing or denoting the differences
      between objects, or the qualities by which one is known
      from others; exercise of discernment; discrimination.
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            To take away therefore that error, which confusion
            breedeth, distinction is requisite.   --Hooker.
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   3. That which distinguishes one thing from another;
      distinguishing quality; sharply defined difference; as,
      the distinction between real and apparent good.
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            The distinction betwixt the animal kingdom and the
            inferior parts of matter.             --Locke.
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   4. Estimation of difference; regard to differences or
      distinguishing circumstance.
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            Maids, women, wives, without distinction, fall.
                                                  --Dryden.
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   5. Conspicuous station; eminence; superiority; honorable
      estimation; as, a man of distinction.
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            Your country's own means of distinction and defense.
                                                  --D. Webster.

   Syn: Difference; variation, variety; contrast; diversity;
        contrariety; disagreement; discrimination; preference;
        superiority; rank; note; eminence.
        [1913 Webster]

WordNet (r) 3.0 (2006):

distinction
    n 1: a discrimination between things as different and distinct;
         "it is necessary to make a distinction between love and
         infatuation" [syn: differentiation, distinction]
    2: high status importance owing to marked superiority; "a
       scholar of great eminence" [syn: eminence, distinction,
       preeminence, note]
    3: a distinguishing quality; "it has the distinction of being
       the cheapest restaurant in town"
    4: a distinguishing difference; "he learned the distinction
       between gold and lead"