Pertaining to the depositional environment of the deepest area of the ocean basins, the abyss. The depositional energy is low, the abyssal plain is flat and nearly horizontal, and fine-grained sedimen [..]

1690s, "unfathomable, unsearchably deep, like an abyss," from abyss + -al (1). Since 19c. mainly "inhabiting or belonging to the depths of the ocean" (used especially of the zone o [..]

(adj) relating to ocean depths from 2000 to 5000 meters(adj) resembling an abyss in depth; so deep as to be unmeasurable

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

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).

An area of the ocean from approximately 10,000 to 20,000 feet (3,000 to 6,000) beneath the surface.

Belonging to, or resembling, an abyss; unfathomable. <physics> Abyssal zone, one of the belts or zones into which Sir E. Forbes divides the bottom of the sea in describing its plants, animals, etc. It is the one furthest from the shore, embracing all beyond one hundred fathoms deep. Hence, abyssal animals, plants, etc. Origin: Cf. Abysmal. (0 [..]

referring to the deep sea or abyss

(archaic) Belonging to, or resembling, an abyss; unfathomable.physical geography *physical geography