The Collaborative International Dictionary of English v.0.48:

Ream \Ream\, v. t. [imp. & p. p. Reamed (r[=e]md); p. pr. &
   vb. n. Reaming.] [Cf. G. r[aum]umen to remove, to clear
   away, fr. raum room. See Room.]
   To bevel out, as the mouth of a hole in wood or metal; in
   modern usage, to enlarge or dress out, as a hole, with a
   reamer.
   [1913 Webster]