The Collaborative International Dictionary of English v.0.48:

Ursus \Ur"sus\, n. [L., a bear.] (Zool.)
   A genus of Carnivora including the common bears.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Ursus
    n 1: type genus of Ursidae: brown bears; in some classifications
         genus Ursus includes all bears [syn: Ursus, genus
         Ursus]