The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

archbishop
    n 1: a bishop of highest rank

The Devil's Dictionary (1881-1906):

ARCHBISHOP, n.  An ecclesiastical dignitary one point holier than a
bishop.

    If I were a jolly archbishop,
    On Fridays I'd eat all the fish up --
    Salmon and flounders and smelts;
    On other days everything else.
                                                              Jodo Rem