Abaddon
ABADDON, a Hebrew word meaning "destruction." In poetry it comes to mean "place of destruction," and so the underworld or Sheol (cf. Job xxvi. 6; Prov. xv. 11). In Rev. ix. 11 Abaddon ((Abaddon) is used of hell personified, the prince of the underworld. The term is here explained as Apollyon (q.v.), the "destroyer.', W. Baudissin (Herzog-Hauck, Realencyklo padie) notes that Hades and Abaddon in Rabbinic writings are employed as personal names, just as shemayya in Dan. iv. 23, shamayim ("heaven"), and makom ("place") among the Rabbins, are used of God.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)