Definition of "abyss"

abyss

/əˈbɪs/

noun
plural abysses
1. Hell; the bottomless pit; primeval chaos; a confined subterranean ocean.
  Quotations
  'You cannot enter here,' said Gandalf, and the huge shadow halted. 'Go back to the abyss prepared for you! Go back! Fall into the nothingness that awaits you and your Master. Go!'
  1955, J. R. R. Tolkien, The Lord of the Rings: Return of the King‎, page 190
2. (frequently figurative) A bottomless or unfathomed depth, gulf, or chasm; hence, any deep, immeasurable; any void space.
  Quotations
  Below is the deep abyss of the Lauterbrunnen valley, and at its head a stately semi-circle of mountains, with the pyramidal Lauterbrunnen Breithorn as the centre-piece.
  1960 December, Voyageur, “The Mountain Railways of the Bernese Oberland”, in Trains Illustrated, page 752
3. Anything infinite, immeasurable, or profound.
4. Moral depravity; vast intellectual or moral depth.
5. (with article) An impending catastrophic happening.
6. (heraldry) The center of an escutcheon.
7. (oceanography) The abyssal zone.
8. (figurative) A difference, especially a large difference, between groups.