The Collaborative International Dictionary of English v.0.48:

Rafter \Raft"er\, v. t.
   1. To make into rafters, as timber.
      [1913 Webster]

   2. To furnish with rafters, as a house.
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   3. (Agric.) To plow so as to turn the grass side of each
      furrow upon an unplowed ridge; to ridge. [Eng.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rafter \Raft"er\ (r[.a]ft"[~e]r), n.
   A raftsman.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rafter \Raft"er\, n. [AS. r[ae]fter; akin to E. raft, n. See
   Raft.] (Arch.)
   Originally, any rough and somewhat heavy piece of timber.
   Now, commonly, one of the timbers of a roof which are put on
   sloping, according to the inclination of the roof. See
   Illust. of Queen-post.
   [1913 Webster]

         [Courtesy] oft is sooner found in lowly sheds,
         With smoky rafters, than in tapestry halls. --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

rafter
    n 1: one of several parallel sloping beams that support a roof
         [syn: rafter, balk, baulk]
    2: someone who travels by raft [syn: raftsman, raftman,
       rafter]
    v 1: provide (a ceiling) with rafters

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "rafter":
   H beam, I beam, angle rafter, balk, batten, boom, box girder,
   breastsummer, corbel, crossbeam, crosstie, footing beam, girder,
   hammer beam, hip rafter, joist, lattice girder, lintel,
   plate girder, ridge strut, ridgepole, sill, sleeper, sprit,
   stringpiece, strut, stud, studding, summer, summertree, tie,
   tie beam, transom, transverse, trave, traverse, truss,
   truss beam