Source : Webster's Revised Unabridged Dictionary (1913)

Celluloid \Cel"lu*loid`\ (s[e^]l"[-u]*loid), n. [Cellulose +
   -oid.]
   A substance composed essentially of gun cotton and camphor,
   and when pure resembling ivory in texture and color, but
   variously colored to imitate coral, tortoise shell, amber,
   malachite, etc. It is used in the manufacture of jewelry and
   many small articles, as combs, brushes, collars, and cuffs;
   -- originally called {xylonite}.

Source : WordNet®

celluloid
     adj : artificial as if portrayed in a film; "a novel with flat
           celluloid characters" [syn: {synthetic}]
     n 1: 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
     2: a medium that disseminates moving pictures; "theater pieces
        transferred to celluloid"; "this story would be good
        cinema"; "film coverage of sporting events" [syn: {film},
        {cinema}]