Source : Webster's Revised Unabridged Dictionary (1913)

Mediatorial \Me`di*a*to"ri*al\, a.
   Of or pertaining to a mediator, or to mediation; mediatory;
   as, a mediatorial office. -- {Me`di*a*to"ri*al*ly}, adv.

         My measures were . . . healing and mediatorial.
                                                  --Burke.