ebonite vs hard rubber

ebonite and hard rubber both are nouns.

Word	Noun	Adjective	Verb	Adverb
ebonite	Yes	No	No	No
hard rubber	Yes	No	No	No

As nouns, ebonite and hard rubber are synonyms defined as:

ebonite and hard rubber: a hard nonresilient rubber formed by vulcanizing natural rubber

Other synonyms of ebonite include vulcanite.

ebonite (noun)	hard rubber (noun)
a hard nonresilient rubber formed by vulcanizing natural rubber	a hard nonresilient rubber formed by vulcanizing natural rubber