硬こう質しつゴム

noun

hard rubber; ebonite; vulcanite

Refers to rigid, hardened rubber materials such as ebonite or vulcanite, often used in industrial or electrical contexts.

• 硬こう質しつゴムは電でん気き絶ぜつ縁えん体たいとして使つかわれることがある。

  Hard rubber is sometimes used as an electrical insulator.