The Collaborative International Dictionary of English v.0.48:

Ballistics \Bal*lis"tics\, n. [Cf. F. balistique. See
   Ballista.]
   The science or art of hurling missile weapons by the use of
   an engine. --Whewell.
   [1913 Webster]

   2. The science treating the motion of projectiles in flight,
      especially when they are in free fall within the earth's
      gravitational field.
      [PJC]

   3. The study of the characteristics of a cartridge fired from
      a firearm, and of the processes occurring during the
      discharge of a firearm.
      [PJC]

   4. The division within a police department which studies the
      characteristics of cartridges fired from a firearm; the
      ballistics department. The characteristics of the weapons
      and bullets fired may be used as evidence in criminal
      investigations.
      [PJC]

WordNet (r) 3.0 (2006):

ballistics
    n 1: the trajectory of an object in free flight [syn:
         ballistics, ballistic trajectory]
    2: the science of flight dynamics