Source : Webster's Revised Unabridged Dictionary (1913)

   4. Greatness; grandeur. ``With plain, heroic magnitude of
      mind.'' --Milton.

   5. Greatness, in reference to influence or effect;
      importance; as, an affair of magnitude.

            The magnitude of his designs.         --Bp. Horsley.

   {Apparent magnitude} (Opt.), the angular breadth of an object
      viewed as measured by the angle which it subtends at the
      eye of the observer; -- called also {apparent diameter}.
      

   {Magnitude of a star} (Astron.), the rank of a star with
      respect to brightness. About twenty very bright stars are
      said to be of first magnitude, the stars of the sixth
      magnitude being just visible to the naked eye. Telescopic
      stars are classified down to the twelfth magnitude or
      lower. The scale of the magnitudes is quite arbitrary, but
      by means of photometers, the classification has been made
      to tenths of a magnitude.