The Collaborative International Dictionary of English v.0.48:

Diphyodont \Diph"y*o*dont\, a. [Gr. ? double (di- = di`s- twice
   + ? to produce) + 'odoy`s, 'odo`ntos, tooth.] (Anat.)
   Having two successive sets of teeth (deciduous and
   permanent), one succeeding the other; as, a diphyodont
   mammal; diphyodont dentition; -- opposed to monophyodont.
   -- n. An animal having two successive sets of teeth.
   [1913 Webster]