BESTIARY Meaning of BESTIARY in English [ 'bɛstɪəri ]■ noun ( plural bestiaries ) a treatise on animals, especially a medieval work with a moralizing tone.OriginC19: from med. L. bestiarium , from L. bestia 'beast'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004