1. [n]  a bishop having jurisdiction over a diocese
2. [adj]  belonging to or governing a diocese

DIOCESAN is a 8 letter word that starts with D.

1. \Di*oc"e*san\ (?; 277), a. [LL. dioecesanus: cf. F.
   dioc['e]sain.]
   Of or pertaining to a diocese; as, diocesan missions.
   
   

2. \Di*oc"e*san\, n.
   1. A bishop, viewed in relation to his diocese; as, the
      diocesan of New York.
   
   2. pl. The clergy or the people of a diocese. --Strype.