Source : Webster's Revised Unabridged Dictionary (1913)

Ex libris \Ex` li"bris\ [L. ex from + libris books.]
   An inscription, label, or the like, in a book indicating its
   ownership; esp., a bookplate.

Source : WordNet®

ex libris
     n : a label identifying the owner of a book in which it is
         pasted [syn: {bookplate}]