Source : Webster's Revised Unabridged Dictionary (1913)

Bestiary \Bes"ti*a*ry\, n. [LL. bestiarium, fr. L. bestiarius
   pert. to beasts, fr. bestia beast: cf. F. bestiaire.]
   A treatise on beasts; esp., one of the moralizing or
   allegorical beast tales written in the Middle Ages.

         A bestiary . . . in itself one of the numerous
         medi[ae]val renderings of the fantastic mystical
         zo["o]logy.                              --Saintsbury.

Source : WordNet®

bestiary
     n : a medieval book (usually illustrated) with allegorical and
         amusing descriptions of real and fabled animals