Definitions of celluloid:

• noun:   highly flammable substance made from cellulose nitrate and camphor; used in e.g. motion-picture and X-ray film; its use has decreased with the development of nonflammable thermoplastics
• noun:   a medium that disseminates moving pictures

  Example: "Theater pieces transferred to celluloid"

• adjective:   artificial as if portrayed in a film

  Example: "A novel with flat celluloid characters"