The Collaborative International Dictionary of English v.0.48:

Contrast \Con"trast\ (k[o^]n"tr[.a]st), n. [F. contraste: cf.
   It. contrasto.]
   1. The act of contrasting, or the state of being contrasted;
      comparison by contrariety of qualities.
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            place the prospect of the soul
            In sober contrast with reality.       --Wordsworth.
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   2. Opposition or dissimilitude of things or qualities;
      unlikeness, esp. as shown by juxtaposition or comparison.
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            The contrasts and resemblances of the seasons.
                                                  --Whewell.
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   3. (Fine Arts) The opposition of varied forms, colors, etc.,
      which by such juxtaposition more vividly express each
      other's peculiarities.                      --Fairholt.
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The Collaborative International Dictionary of English v.0.48:

Contrast \Con*trast"\, v. i. [imp. & p. p. Contrasted; p. pr.
   & vb. n. Contrasting.] [F. contraster, LL. contrastare to
   resist, withstand, fr. L. contra + stare to stand. See
   Stand.]
   To stand in opposition; to exhibit difference, unlikeness, or
   opposition of qualities.
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         The joints which divide the sandstone contrast finely
         with the divisional planes which separate the basalt
         into pillars.                            --Lyell.
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The Collaborative International Dictionary of English v.0.48:

Contrast \Con*trast"\, v. t.
   1. To set in opposition, or over against, in order to show
      the differences between, or the comparative excellences
      and defects of; to compare by difference or contrariety of
      qualities; as, to contrast the present with the past.
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   2. (Fine Arts) To give greater effect to, as to a figure or
      other object, by putting it in some relation of opposition
      to another figure or object.
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            the figures of the groups must not be all on side .
            . . but must contrast each other by their several
            position.                             --Dryden.
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WordNet (r) 3.0 (2006):

contrast
    n 1: the opposition or dissimilarity of things that are
         compared; "in contrast to", "by contrast" [syn: contrast,
         direct contrast]
    2: the act of distinguishing by comparing differences
    3: a conceptual separation or distinction; "there is a narrow
       line between sanity and insanity" [syn: line, dividing
       line, demarcation, contrast]
    4: the perceptual effect of the juxtaposition of very different
       colors
    5: the range of optical density and tone on a photographic
       negative or print (or the extent to which adjacent areas on a
       television screen differ in brightness)
    v 1: put in opposition to show or emphasize differences; "The
         middle school teacher contrasted her best student's work
         with that of her weakest student"
    2: to show differences when compared; be different; "the
       students contrast considerably in their artistic abilities"
       [syn: contrast, counterpoint]