ˈsɛljəˌlɔɪd ˈsɪn.ə.mə ˈsɪn.ɪ.mə fɪlm sɪnˈθɛtɪk artificial as if portrayed in a film a novel with flat celluloid characters a medium that disseminates moving pictures theater pieces transferred to celluloid this story would be good cinema film coverage of sporting events 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