The Collaborative International Dictionary of English v.0.48:

Abbreviator \Ab*bre"vi*a`tor\, n. [LL.: cf. F. abbr['e]viateur.]
   1. One who abbreviates or shortens.
      [1913 Webster]

   2. One of a college of seventy-two officers of the papal
      court whose duty is to make a short minute of a decision
      on a petition, or reply of the pope to a letter, and
      afterwards expand the minute into official form.
      [1913 Webster]

WordNet (r) 3.0 (2006):

abbreviator
    n 1: one who shortens or abridges or condenses a written work
         [syn: abridger, abbreviator]