a person or thing that directs.

one of a group of persons chosen to control or govern the affairs of a company or corporation

a board of directors.

the person responsible for the interpretive aspects of a stage, film, or television production; the person who supervises the integration of all the elements, as acting, staging, and lighting, required to realize the writer's conception. Compare producer ( def. 3 ) .

the musical conductor of an orchestra, chorus, etc.

the manager or chief executive of certain schools, institutes, government bureaus, etc.

Military . a mechanical or electronic device that continuously calculates firing data for use against an airplane or other moving target.