Bottomless Pit

Concise Bible Dictionary:

The word is ἄβυσσος, literally “without a bottom,” an abyss. From the passages in the Revelation we learn that the abyss is where the Satanic powers are shut up, not where they will be punished, which is in the lake of fire. The demons cast out by the Lord in Luke 8:31³¹And they besought him that he would not command them to go out into the deep. (Luke 8:31) besought Him that He would not send them into the abyss. In Romans 10:7⁷Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.) (Romans 10:7) it is put in contrast to the heavens. In Revelation 9:1-11¹And the fifth angel sounded, and I saw a star fall from heaven unto the earth: and to him was given the key of the bottomless pit. ²And he opened the bottomless pit; and there arose a smoke out of the pit, as the smoke of a great furnace; and the sun and the air were darkened by reason of the smoke of the pit. ³And there came out of the smoke locusts upon the earth: and unto them was given power, as the scorpions of the earth have power. ⁴And it was commanded them that they should not hurt the grass of the earth, neither any green thing, neither any tree; but only those men which have not the seal of God in their foreheads. ⁵And to them it was given that they should not kill them, but that they should be tormented five months: and their torment was as the torment of a scorpion, when he striketh a man. ⁶And in those days shall men seek death, and shall not find it; and shall desire to die, and death shall flee from them. ⁷And the shapes of the locusts were like unto horses prepared unto battle; and on their heads were as it were crowns like gold, and their faces were as the faces of men. ⁸And they had hair as the hair of women, and their teeth were as the teeth of lions. ⁹And they had breastplates, as it were breastplates of iron; and the sound of their wings was as the sound of chariots of many horses running to battle. ¹⁰And they had tails like unto scorpions, and there were stings in their tails: and their power was to hurt men five months. ¹¹And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon. (Revelation 9:1‑11), to a star fallen from heaven the key of the abyss is given, and on its being opened great moral darkness rises, out of which destructive agents proceed: Abaddon (Apollyon) “the destroyer” is their king. The future Roman empire is represented as a beast rising out of (receiving in its last head power from) the abyss (Rev. 11:7⁷And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them. (Revelation 11:7); Rev. 17:8⁸The beast that thou sawest was, and is not; and shall ascend out of the bottomless pit, and go into perdition: and they that dwell on the earth shall wonder, whose names were not written in the book of life from the foundation of the world, when they behold the beast that was, and is not, and yet is. (Revelation 17:8)). Satan will be confined in the abyss during the thousand years of the millennium (Rev. 20:1, 3¹And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand. (Revelation 20:1)
³And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season. (Revelation 20:3)). (The above are all the passages where the Greek word occurs.)