Where does “abyssalis” come from?

abyssalis (Late Latin) comes from Latin abyssus, from Ancient Greek ἄβυσσος, from Ancient Greek ἀ-, from Proto-Hellenic hə-, from Proto-Indo-European sm̥-, from Proto-Indo-European sem- — together, one.

abyssalis (Late Latin): Of, pertaining to or resembling an abyss;...