The Collaborative International Dictionary of English v.0.48:

Reamer \Ream"er\ (-[~e]r), n.
   One who, or that which, reams; specifically, an instrument
   with cutting or scraping edges, used, with a twisting motion,
   for enlarging a round hole, as the bore of a cannon, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

reamer
    n 1: a squeezer with a conical ridged center that is used for
         squeezing juice from citrus fruit [syn: reamer, juicer,
         juice reamer]
    2: a drill that is used to shape or enlarge holes