Source : Webster's Revised Unabridged Dictionary (1913)

Ebonite \Eb"on*ite\, n. (Chem.)
   A hard, black variety of vulcanite. It may be cut and
   polished, and is used for many small articles, as combs and
   buttons, and for insulating material in electric apparatus.

Source : WordNet®

ebonite
     n : a hard nonresilient rubber formed by vulcanizing natural
         rubber [syn: {hard rubber}, {vulcanite}]