The Collaborative International Dictionary of English v.0.48:

Dinothere \Di"no*there\, Dinotherium \Di`no*the"ri*um\, n. [NL.
   dinotherium, fr. Gr. deino`s terrible + qhri`on beast.]
   (Paleon.)
   A large extinct proboscidean mammal from the miocene beds of
   Europe and Asia. It is remarkable for a pair of tusks
   directed downward from the decurved apex of the lower jaw.
   [1913 Webster]