The Collaborative International Dictionary of English v.0.48:

magnum \mag"num\ (m[a^]g"n[u^]m), a.
   1. (Firearms) Having a larger charge than usual for a
      cartridge of the same caliber; -- of cartridges for
      handgun; as, a .44 magnum cartridge.
      [PJC]

   2. (Firearms) Designed to use a cartridge with a larger
      charge than usual for handguns of the same caliber; -- of
      handguns; as, a .44 magnum pistol.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Magnum \Mag"num\ (m[a^]g"n[u^]m), n. [Neut. sing. of L. magnus
   great.]
   1. A large wine bottle.
      [1913 Webster]

            They passed the magnum to one another freely. --Sir
                                                  W. Scott.
      [1913 Webster]

   2. (Anat.) A bone of the carpus at the base of the third
      metacarpal bone.
      [1913 Webster]

   3. A magnum pistol, or the cartridge such a pistol uses; as,
      he always carried a .44 magnum.
      [PJC]

WordNet (r) 3.0 (2006):

magnum
    n 1: a large wine bottle for liquor or wine

The Free On-line Dictionary of Computing (30 December 2018):

MAGNUM

   A database language for DEC-10's, used internally by
   Tymshare, Inc..  MAGNUM was designed in the late 1970's by
   Dale Jordan, Rich Strauss and Dave McQuoid originally, and was
   written in BLISS-10.  It was the world's first commercial
   relational database.  It was in the process of being written
   in 1976.

   (1995-01-25)