director

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One that supervises, controls, or manages.
• noun A member of a group of persons chosen to control or govern the affairs of an institution or corporation.
• noun A person who supervises the creative aspects of a dramatic production or film and instructs the actors and crew.
• noun The conductor of an orchestra or chorus.
• noun An electronic device that continually calculates and displays information used for firing weapons at moving targets, such as missiles or aircraft.

from The Century Dictionary.

• noun In geometry, a fixed guiding line.
• noun The small printed or written letter inserted as a guide in the space to be afterward filled by the designer or illuminator of the large initial.
• noun One who directs; one who guides, superintends, governs, or manages.
• noun Specifically— One of a number of persons, appointed or elected under provision of law, having authority to manage and direct the affairs of a corporation or company. All the directors collectively constitute a board of directors. They are agents of the corporation, and not of the stockholders. Generally they are elected for one year.
• noun In music, the leader or conductor of a company of vocal or instrumental performers: as, a choir director; an orchestral director.
• noun Anything that directs or controls.
• noun Specifically — In surgery, a grooved probe, intended to direct the edge of the knife or scissors in opening sinuses or fistulæ or making incisions generally, In electricity, a metallic instrument on a glass handle connected by a chain with the pole of a battery, and applied to the part of the body to which a shock is to be sent.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who, or that which, directs; one who regulates, guides, or orders; a manager or superintendent.
• noun One of a body of persons appointed to manage the affairs of a company or corporation.
• noun (Mech.) A part of a machine or instrument which directs its motion or action.
• noun (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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun One who directs; the person in charge of managing a department or directorate (e.g., director of engineering), project, or production (as in a show or film, e.g., film director).
• noun A device that displays graphical information concerning the targets of a weapons system in real time.
• noun chemistry The common axis of symmetry of the molecules of a liquid crystal.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the person who directs the making of a film
• noun someone who supervises the actors and directs the action in the production of a show
• noun member of a board of directors
• noun the person who leads a musical group
• noun someone who controls resources and expenditures