BOTTOMLESS, PIT

bot'-um-les, (to phrear tes abussou, "the pit of the abyss," Revelation 9:1-2 the King James Version): In the Revised Version (British and American), he abussos (always an adjective in classical authors = "bottomless") is uniformly rendered "the abyss" (which see) (Luke 8:31; Romans 10:7; Revelation 9:11; 11:7; 17:8; 20:1,3).

From the International Standard Bible Encyclopedia
Edited by James Orr, published in 1939 by Wm. B. Eerdmans Publishing Co.