The Collaborative International Dictionary of English v.0.48:

Tome \Tome\ (t[=o]m), n. [F. tome (cf. It., Sp., & Pg. tomo), L.
   tomus, fr. Gr. ? a piece cut off, a part of a book, a volume,
   akin to ? to cup, and perhaps to L. tondere to shear, E.
   tonsure. Cf. Anatomy, Atom, Entomology, Epitome. ]
   As many writings as are bound in a volume, forming part of a
   larger work; a book; -- usually applied to a ponderous
   volume.
   [1913 Webster]

         Tomes of fable and of dream.             --Cowper.
   [1913 Webster]

         A more childish expedient than that to which he now
         resorted is not to be found in all the tomes of the
         casuists.                                --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tome
    n 1: a (usually) large and scholarly book