superhard

Adjective

 * 1) Having a very high hardness.
 * 2) Highly strengthened against attack.
 * 3)  Having a hardness between that of boron nitride and that of diamond.
 * 1)  Having a hardness between that of boron nitride and that of diamond.

Noun

 * 1)  A tyre whose compound is harder than a normal hard tyre.