The Collaborative International Dictionary of English v.0.48:

Discern \Dis*cern"\, v. t. [imp. & p. p. Discerned; p. pr. &
   vb. n. Discerning.] [F. discerner, L. discernere,
   discretum; dis- + cernere to separate, distinguish. See
   Certain, and cf. Discreet.]
   1. To see and identify by noting a difference or differences;
      to note the distinctive character of; to discriminate; to
      distinguish.
      [1913 Webster]

            To discern such buds as are fit to produce blossoms.
                                                  --Boyle.
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            A counterfeit stone which thine eye can not discern
            from a right stone.                   --Robynson
                                                  (More's
                                                  Utopia).
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   2. To see by the eye or by the understanding; to perceive and
      recognize; as, to discern a difference.
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            And [I] beheld among the simple ones, I discerned
            among the youths, a young man void of understanding.
                                                  --Prov. vii.
                                                  7.
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            Our unassisted sight . . . is not acute enough to
            discern the minute texture of visible objects.
                                                  --Beattie.
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            I wake, and I discern the truth.      --Tennyson.

   Syn: To perceive; distinguish; discover; penetrate;
        discriminate; espy; descry; detect. See Perceive.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Discern \Dis*cern"\, v. i.
   1. To see or understand the difference; to make distinction;
      as, to discern between good and evil, truth and falsehood.
      [1913 Webster]

            More than sixscore thousand that cannot discern
            between their right hand their left.  --Jonah iv.
                                                  11.
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   2. To make cognizance. [Obs.] --Bacon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

discern
    v 1: detect with the senses; "The fleeing convicts were picked
         out of the darkness by the watchful prison guards"; "I
         can't make out the faces in this photograph" [syn: spot,
         recognize, recognise, distinguish, discern, pick
         out, make out, tell apart]