Abaddon - (Easton's Bible Dictionary)
Destruction, the Hebrew name (equivalent to the Greek Apollyon, i.e., destroyer) of "the angel of the bottomless pit" (Rev. 9:11). It is rendered "destruction" in Job 28:22; 31:12; 26:6; Prov. 15:11; 27:20. In the last three of these passages the Revised Version retains the word "Abaddon." We may regard this word as a personification of the idea of destruction, or as sheol, the realm of the dead.