n. 硬橡胶

[化] 硬质胶; 硬质橡胶

[ noun ]
a hard nonresilient rubber formed by vulcanizing natural rubber
<noun.substance>

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.