Source : Webster's Revised Unabridged Dictionary (1913)

Mylodon \Myl"o*don\, n. [Gr. ? a mill + ?, ?, a tooth.]
   (Paleon.)
   An extinct genus of large slothlike American edentates,
   allied to Megatherium.

Source : WordNet®

mylodon
     n : large (bear-sized) extinct edentate mammal of the
         Pleistocene in South America