From 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]