The bottomless pit is the place of restraint for demonic powers — a kind of prison from which they cannot escape except by divine permission. In Revelation 9:1-2, a fallen star is given the key to the bottomless pit, and out of it comes smoke and locust-creatures that torment the unsealed. In Revelation 11:7, "the beast that ascends out of the bottomless pit" makes war against the two witnesses. In Revelation 17:8, "the beast that you saw was, and is not, and will ascend out of the bottomless pit." Most significantly, Revelation 20:1-3 shows an angel with "the key of the bottomless pit" binding Satan himself for a thousand years. The bottomless pit is not hell proper (the lake of fire) but a place of demonic confinement. The demons Jesus cast out of the Gadarene demoniac begged "that He would not command them to go out into the abyss" (Luke 8:31) — they knew the place and feared it. The bottomless pit is one more reminder that every hostile spiritual power operates on a leash held by Christ.
Revelation 20:1-3 — "Then I saw an angel coming down from heaven, having the key to the bottomless pit and a great chain in his hand. He laid hold of the dragon, that serpent of old... and he cast him into the bottomless pit."
Revelation 9:1-2 — "Then the fifth angel sounded: And I saw a star fallen from heaven to the earth. To him was given the key to the bottomless pit."
Luke 8:31 — "And they begged Him that He would not command them to go out into the abyss."
G12 — ἄβυσσος (abyssos) — abyss, bottomless pit; the place of demonic restraint
G12 — ἄβυσσος (abyssos) — abyss, bottomless pit; the place of demonic restraint