The Collaborative International Dictionary of English v.0.48:

Overseer \O`ver*seer"\, n.
   One who oversees; a superintendent; a supervisor; as, an
   overseer of a mill; specifically, one or certain public
   officers; as, an overseer of the poor; an overseer of
   highways.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overseer
    n 1: a person who directs and manages an organization [syn:
         overseer, superintendent]