ABYSS
Greek, “abyssos” = “bottomless.” Term used in the LXX version to translate the Hebrew word meaning “depth.” In the Old Testament it means the universal sea that enveloped everything that existed, heaven and earth.
On the second day God separates the waters that were above the firmament from those that were below. The word “deep” will henceforth refer to these waters (Gen. 1:2; Deut. 33:13; Ps. 104:6).
In the NT it appears especially in Revelation, where we see that the abyss is the place where satanic powers are locked up; His punishment will be later, in the lake of fire (Rev. 9:1, 2; 20:10).
It is from Revelation (Rev. 9:1-11) that it is seen that a star fallen from heaven receives the keys of the abyss, a thick moral darkness arising when it is opened, and destructive agents emerging from it: Abaddon (in Hebrew), or Apollyon (in Greek), the “destroyer”, is their king.
The future Roman empire is represented as a beast rising from the abyss (Rev. 11:7; 17:8). During the Millennium, Satan will be confined to the abyss, completely unable to deceive and act (Rev. 20:1, 3). In Lk. 8:31, the demons beg Christ not to cast them into the abyss; in Ro. 10:7 appears in contrast to the heavens.