The Collaborative International Dictionary of English v.0.48:

Director \Di*rect"or\, n. [Cf. F. directeur.]
   1. One who, or that which, directs; one who regulates,
      guides, or orders; a manager or superintendent.
      [1913 Webster]

            In all affairs thou sole director.    --Swift.
      [1913 Webster]

   2. One of a body of persons appointed to manage the affairs
      of a company or corporation; as, the directors of a bank,
      insurance company, or railroad company.
      [1913 Webster]

            What made directors cheat in South-Sea year? --Pope.
      [1913 Webster]

   3. (Mech.) A part of a machine or instrument which directs
      its motion or action.
      [1913 Webster]

   4. (Surg.) A slender grooved instrument upon which a knife is
      made to slide when it is wished to limit the extent of
      motion of the latter, or prevent its injuring the parts
      beneath.
      [1913 Webster]

WordNet (r) 3.0 (2006):

director
    n 1: someone who controls resources and expenditures [syn:
         director, manager, managing director]
    2: member of a board of directors
    3: someone who supervises the actors and directs the action in
       the production of a show [syn: director, theater
       director, theatre director]
    4: the person who directs the making of a film [syn: film
       director, director]
    5: the person who leads a musical group [syn: conductor,
       music director, director]

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "director":
   Kapellmeister, MC, administrator, auteur, ballyhoo man,
   band leader, band major, bandmaster, banker, barker, baron,
   big boss, big businessman, big cheese, boss, business leader,
   businessman, callboy, captain, captain of industry, castellan,
   chairman, chatelain, chatelaine, chief, cicerone, commandant,
   commander, conductor, costume designer, costumer, costumier,
   drum major, emcee, enterpriser, entrepreneur, equestrian director,
   executive, exhibitor, financier, foreman, gaffer, governor, guide,
   head, headman, helmsman, impresario, industrialist, intendant,
   king, kingpin, leader, little businessman, maestro, magnate,
   makeup man, man of commerce, manager, master, master of ceremonies,
   number one, official, orchestra leader, overseer, pilot,
   playreader, president, principal, producer, prompter, ringmaster,
   ruler, scenewright, set designer, showman, skipper, spieler,
   stage director, stage manager, steersman, superintendent,
   supervisor, symphonic conductor, theater man, theatrician,
   ticket collector, top dog, top executive, tycoon, usher, usherer,
   usherette, vice-president