Source : Webster's Revised Unabridged Dictionary (1913)

Illustrate \Il*lus"trate\, v. t. [imp. & p. p. {Illustrated}; p.
   pr. & vb. n. {Illustrating}.] [L. illustratus, p. p. of
   illustrare to illustrate, fr. illustris bright. See
   {Illustrious}.]
   1. To make clear, bright, or luminous.

            Here, when the moon illustrates all the sky.
                                                  --Chapman.

   2. To set in a clear light; to exhibit distinctly or
      conspicuously. --Shak.

            To prove him, and illustrate his high worth.
                                                  --Milton.

   3. To make clear, intelligible, or apprehensible; to
      elucidate, explain, or exemplify, as by means of figures,
      comparisons, and examples.

   4. To adorn with pictures, as a book or a subject; to
      elucidate with pictures, as a history or a romance.

   5. To give renown or honor to; to make illustrious; to
      glorify. [Obs.]

            Matter to me of glory, whom their hate Illustrates.
                                                  --Milton.

Illustrate \Il*lus"trate\, a. [L. illustratus, p. p.]
   Illustrated; distinguished; illustrious. [Obs.]

         This most gallant, illustrate, and learned gentleman.
                                                  --Shak.

Source : WordNet®

illustrate
     v 1: clarify by giving an example of [syn: {exemplify}, {instance}]
     2: depict with an illustration
     3: e.g., illustrate a book with drawings