ah-biss-al At or of the ocean depths or floor, ii) at or from a great depth in the earth's crust; plutonic.

relating to ocean depths from 2000 to 5000 meters

so deep as to be unmeasurable; "the abyssal depths of the ocean"

ocean depths greater than 4000 meters. The floor of the deep ocean, from 4000-6000 meters, is called the abyssal plain.

referring to the deep sea or abyss

on or near the ocean floor in the deep ocean. Abyssal regions are characterized by complete lack of light, extremely high water pressure, low nutrient availability, and continuous cold (3 degrees C).