Source : Webster's Revised Unabridged Dictionary (1913)

Reflection \Re*flec"tion\ (r?*fl?k"sh?n), n. [L. reflexio: cf.
   F. r['e]flexion. See {Riflect}.] [Written also {reflexion}.]
   1. The act of reflecting, or turning or sending back, or the
      state of being reflected. Specifically:
      (a) The return of rays, beams, sound, or the like, from a
          surface. See {Angle of reflection}, below.

                The eye sees not itself, But by reflection, by
                some other things.                --Shak.
      (b) The reverting of the mind to that which has already
          occupied it; continued consideration; meditation;
          contemplation; hence, also, that operation or power of
          the mind by which it is conscious of its own acts or
          states; the capacity for judging rationally,
          especially in view of a moral rule or standard.

                By reflection, . . . I would be understood to
                mean, that notice which the mind takes of its
                own operations, and the manner of them, by
                reason whereof there come to be ideas of these
                operations in the understanding.  --Locke.

                This delight grows and improves under thought
                and reflection.                   --South.

   2. Shining; brightness, as of the sun. [Obs.] --Shak.

   3. That which is produced by reflection. Specifically:
      (a) An image given back from a reflecting surface; a
          reflected counterpart.

                As the sun water we can bear, Yet not the sun,
                but his reflection, there.        --Dryden.
      (b) A part reflected, or turned back, at an angle; as, the
          reflection of a membrane.
      (c) Result of meditation; thought or opinion after
          attentive consideration or contemplation; especially,
          thoughts suggested by truth.

                Job's reflections on his once flourishing estate
                did at the same time afflict and encourage him.
                                                  --Atterbury.

   4. Censure; reproach cast.

            He died; and oh! may no reflection shed Its
            poisonous venom on the royal dead.    --Prior.

   5. (Physiol.) The transference of an excitement from one
      nerve fiber to another by means of the nerve cells, as in
      reflex action. See {Reflex action}, under {Reflex}.

   {Angle of reflection}, the angle which anything, as a ray of
      light, on leaving a reflecting surface, makes with the
      perpendicular to the surface.

   {Angle of total reflection}. (Opt.) Same as {Critical angle},
      under {Critical}.

   Syn: Meditation; contemplation; rumination; cogitation;
        consideration; musing; thinking.

Source : WordNet®

angle of reflection
     n : the angle between a reflected ray and a line perpendicular
         to the reflecting surface at the point of incidence