Developer

Webster's Dictionary of the English Language

·noun One who, or that which, develops.

II. Developer ·add. ·noun One that develops.

III. Developer ·add. ·noun A chemical bath or reagent used in developing photographs.

IV. Developer ·add. ·noun A reagent used to produce an ingrain color by its action upon some substance on the fiber.

V. Developer ·noun A reagent by the action of which the latent image upon a photographic plate, after exposure in the camera, or otherwise, is developed and visible.