Where does “ῥῑνόκερως” come from?

ῥῑνόκερως (Ancient Greek) comes from Ancient Greek κέρας, from Proto-Hellenic *kérats.

Ancestry of “ῥῑνόκερως”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	κέρας	horn; horn as a material, or anything made of...
2	Proto-Hellenic	*kérats	—

ῥῑνόκερως — Etymology, Origin & Word History | Etymology Explorer