Definition of: mithridatism

(mith′rə·dā′tiz·əm) noun
Immunity against poisons secured by the administration of gradually increasing doses: so called from King Mithridates VI of Pontus, who is said to have immunized himself by this method. [<obs. mithridiate an antidote against poison <LL mithridatium <Mithridateus of Mithridates]
—mith′ri·dat′ic (-dat′ik) adjective