The term used here in the Greek is “abyss” (the term comes from two words that literally translate as “without bottom”; Revelation 9:1–2, Revelation 9:11; Revelation 11:7; Revelation 17:8). In Luke’s account of the demon-possessed man in the country of the Gerasenes (Luke 8:26–39), the demons entreated Jesus “not to command them to depart into the abyss” (Luke 8:31). This “abyss” is their natural home, where since their rebellion in the beginning, God has “committed them to chains of gloomy darkness” (2 Peter 2:4; Jude 1:6). See also Isaiah 24:21–22.
1 Then I saw an angel coming down from heaven, holding in his hand the key to the bottomless pit and a great chain.