'Bottomless Pit' in the Bible

and they have over them a king, the angel of the bottomless pit, to him the name is Abaddon in Hebrew, and in Greek he has the name Apollyon.

And when they may finish their testimony, the beast which ascends up out of the bottomless pit will make war against them, and conquer them, and slay them.

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

and cast him into the bottomless pit, and shut him up, and put his seal on him, that he should deceive the nations no more, until the thousand years may be fulfilled: after these it behooves him to be loosed a little season.