Synonyms of abyssal

Adjective

1. abyssal

usage: relating to ocean depths from 2000 to 5000 meters

2. abysmal, abyssal, unfathomable, deep (vs. shallow)

usage: resembling an abyss in depth; so deep as to be unmeasurable; "the abyssal depths of the ocean"

Definition and meaning of abyssal (Dictionary)