The Collaborative International Dictionary of English v.0.48:

highlight \highlight\ v. t.
   1. To emphasize or call attention to, by moving into the
      foreground or otherwise making more prominent.

   Syn: foreground, spotlight, play up.
        [WordNet 1.5]

   2. To make (part of a text or image) more prominent,
      especially by making it of a lighter hue or of a different
      color than the remaining part.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

highlight \highlight\ n.
   The part of an image that has the most intense light.
   [PJC]

   2. The most memorable or enjoyable part; -- of events or
      activities; as, the highlight of our trip was the tour of
      the Vatican.
      [PJC]

WordNet (r) 3.0 (2006):

highlight
    n 1: the most interesting or memorable part; "the highlight of
         the tour was our visit to the Vatican" [syn: highlight,
         high spot]
    2: an area of lightness in a picture [syn: highlight,
       highlighting]
    v 1: move into the foreground to make more visible or prominent;
         "The introduction highlighted the speaker's distinguished
         career in linguistics" [syn: foreground, highlight,
         spotlight, play up] [ant: background, downplay,
         play down]
    2: apply a highlighter to one's cheeks or eyebrows in order to
       make them more prominent; "highlight the area above your
       eyebrows"