The Collaborative International Dictionary of English v.0.48:
Coadjutor \Co`ad*ju"tor\, n. [L. See Co-, and Aid.] 1. One who aids another; an assistant; a coworker. [1913 Webster] Craftily outwitting her perjured coadjutor. --Sheridan. [1913 Webster] 2. (R. C. Ch.) The assistant of a bishop or of a priest holding a benefice. [1913 Webster]WordNet (r) 3.0 (2006):
coadjutor n 1: an assistant to a bishop