Hell; the bottomless pit; primeval chaos; a confined subterranean ocean.

(frequently figurative) A bottomless or unfathomed depth, gulf, or chasm; hence, any deep, immeasurable; any void space.

Anything infinite, immeasurable, or profound.

Moral depravity; vast intellectual or moral depth.

(with article) An impending catastrophic happening.

(heraldry) The center of an escutcheon.

(oceanography) The abyssal zone.

(figurative) A difference, especially a large difference, between groups.