'Bottomless Pit' in the Bible

Then the fifth angel blew his trumpet, and I saw a star fallen from heaven upon the earth; and to him was given the key to the bottomless pit.

And he opened the bottomless pit, and out of the pit there went up a smoke like the smoke of a great furnace. And the sun and the air grew dark, because of the smoke out of the pit.

They have a king over them, the angel of the bottomless pit. His name in Hebrew is Abaddon; in Greek he is called Apollyon.

"And when they shall have finished their testimony, the beast that is coming up out of the bottomless pit will make war with them, and overcome them, and kill them.

The beast that you saw was, and is not, and is about to come up out of the bottomless pit, and to go into perdition. And those who dwell on the earth shall wonder, those whose names have never, from the foundation of the world, been written in the Lamb's Book of Life, when they gaze on the beast; how he was and is not, and is to come.

And I saw an angel coming down out of heaven, with the key of the bottomless pit and a great chain in his hand.

and flung him into the bottomless pit, and shut and sealed it over him, so that he should seduce the nations no more, until the thousand years were completed. After that it is necessary to loose him for a little while.