Source : Webster's Revised Unabridged Dictionary (1913)

Penetrate \Pen"e*trate\, v. t. [imp. & p. p. {Penetrated}; p.
   pr. & vb. n. {Penetrating}.] [L. penetratus, p. p. of
   penetrare to penetrate; akin to penitus inward, inwardly, and
   perh. to pens with, in the power of, penus store of food,
   innermost part of a temple.]
   1. To enter into; to make way into the interior of; to effect
      an entrance into; to pierce; as, light penetrates
      darkness.

   2. To affect profoundly through the senses or feelings; to
      touch with feeling; to make sensible; to move deeply; as,
      to penetrate one's heart with pity. --Shak.

            The translator of Homer should penetrate himself
            with a sense of the plainness and directness of
            Homer's style.                        --M. Arnold.

   3. To pierce into by the mind; to arrive at the inner
      contents or meaning of, as of a mysterious or difficult
      subject; to comprehend; to understand.

            Things which here were too subtile for us to
            penetrate.                            --Ray.