The Collaborative International Dictionary of English v.0.48:

Monophyodont \Mon`o*phy"o*dont\, a. [Gr. mo`nos single (mo`nos
   alone + ? to produce) + 'odoy`s, 'odo`ntos, a tooth.] (Anat.)
   Having but one set of teeth; -- opposed to diphyodont.
   [1913 Webster]