The Collaborative International Dictionary of English v.0.48:

Archiater \Ar"chi*a`ter\, n. [L. archiatrus, Gr. ?; pref. ? + ?
   physician, ? to heal.]
   Chief physician; -- a term applied, on the continent of
   Europe, to the first or body physician of princes and to the
   first physician of some cities. --P. Cyc.
   [1913 Webster]