The Collaborative International Dictionary of English v.0.48:

Changer \Chan"ger\, n.
   1. One who changes or alters the form of anything.
      [1913 Webster]

   2. One who deals in or changes money. --John ii. 14.
      [1913 Webster]

   3. One apt to change; an inconstant person.
      [1913 Webster]

   4. an electronic device which changes one replaceable medium
      for another, such as a record changer, which can store
      several records and move each one automatically to the
      playing table; or a CD changer, whch can store multiple
      compact disks and move each one to the reading slot, in a
      sequence determined by the user.
      [PJC]

WordNet (r) 3.0 (2006):

changer
    n 1: a person who changes something; "an inveterate changer of
         the menu" [syn: changer, modifier]
    2: an automatic mechanical device on a record player that causes
       new records to be played without manual intervention [syn:
       record changer, auto-changer, changer]