Polaroid is the brand name of a type of film used to polarize light.
The inventor, Edwin H. Land, later named the company he formed to sell the film (originally called Land-Wheelwright Laboratories, after himself and a wealthy backer who provided start-up money) Polaroid as well.
The Polaroid Corporation is best known, however, for the instant camera (and the photographic film to go with it) that Land developed a few years later.