The Collaborative International Dictionary of English v.0.48:

Desman \Des"man\ (d[e^]s"man), n. [Cf. Sw. desman musk.] (Zool.)
   An amphibious, insectivorous mammal found in Russia (Myogale
   moschata). It is allied to the moles, but is called
   muskrat by some English writers. [Written also
   d[ae]sman.] Desmid