Source : Webster's Revised Unabridged Dictionary (1913)

Archbishop \Arch`bish"op\, n. [AS. arcebisceop, arcebiscop, L.
   archiepiscopus, fr. Gr. 'archiepi`skopos. See {Bishop}.]
   A chief bishop; a church dignitary of the first class (often
   called a metropolitan or primate) who superintends the
   conduct of the suffragan bishops in his province, and also
   exercises episcopal authority in his own diocese.

Source : WordNet®

archbishop
     n : a bishop of highest rank