The Collaborative International Dictionary of English v.0.48:

Mus \Mus\, prop. n.; pl. Mures. [L., a mouse.] (Zool.)
   A genus of small rodents, including the common mouse and rat.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Mus
    n 1: type genus of the Muridae: common house mice; the tips of
         the upper incisors have a square notch [syn: Mus, genus
         Mus]