What does Bathys mean in Latin?

Bathys, a proper noun, means “A small river of Pontus”.

What is the genitive of Bathys?

The genitive singular is Bathyis. Bathys is masculine, third declension.

In classical Latin, [ˈba.tʰys]; in ecclesiastical (church) Latin, [ˈbaː.tis].

proper noun · masculinethird declension

Bathys m sg (genitive Bathyis)

Classical[ˈba.tʰys]Ecclesiastical[ˈbaː.tis]

masculinesingularA small river of Pontus
Arrianus vero inter utrumque tres amnes numeravit, Acinasim, Bathym et AcampsimBut Arrian counted three rivers between them both, the Acinasis, Bathys, and Acampsis1826, Joannes Francisus Gail, Geographi graeci minores (page 455)

Borrowed from Ancient Greek Βαθύς (Bathús).