\Mag"ni*tude\, n. [L. magnitudo, from magnus great.
See {Master}, and cf. {Maxim}.]
1. Extent of dimensions; size; -- applied to things that have
   length, breath, and thickness.
         Conceive those particles of bodies to be so disposed
         amongst themselves, that the intervals of empty
         spaces between them may be equal in magnitude to
         them all.                             --Sir I.
                                               Newton.
2. (Geom.) That which has one or more of the three
   dimensions, length, breadth, and thickness.
3. Anything of which greater or less can be predicated, as
   time, weight, force, and the like.
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.