Abaddon is the anglicized form of the Hebrew word meaning destruction . It is translated as “destruction” in several Old Testament passages. Most commonly, it is used as a synonym for hell. For instance:

• Job 26:6Hell is naked before him, and destruction hath no covering.
  See All... – “Hell is naked before him, and destruction hath no covering.”
• Job 28:22Destruction and death say, We have heard the fame thereof with our ears.
  See All... – “Destruction and death say, We have heard the fame thereof with our ears.”
• Psalm 88:11Shall thy lovingkindness be declared in the grave? or thy faithfulness in destruction?
  See All... – “Shall thy lovingkindness be declared in the grave? or thy faithfulness in destruction?”
• Proverbs 15:11Hell and destruction are before the LORD: how much more then the hearts of the children of men?
  See All... – “Hell and destruction are before the LORD: how much more then the hearts of the children of men?”
• Proverbs 27:20Hell and destruction are never full; so the eyes of man are never satisfied.
  See All... – “Hell and destruction are never full; so the eyes of man are never satisfied.”

In the New Testament, in its only use in the English Bible as Abaddon, it is given as one of the names for the king over the supernatural locusts in the bottomless pit. Revelation 9:11And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.
See All... states, “And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.” Apollyon is the Greek word for destroyer. He is the opposite of the Saviour. Since natural locusts have no king (Proverbs 30:27The locusts have no king, yet go they forth all of them by bands;
See All...), this king is a spiritual being.

Many commentators have identified Abaddon as Satan himself, but it is more likely that the angel of the bottomless pit is one of the princes or powers under the devil (Ephesians 6:12For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
See All...; Colossians 2:15And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.
See All...). The names, Abaddon and Apollyon, connect the angel of the bottomless pit with the “destroyer” of the Old Testament. At the time of the first Passover in Egypt, God promised those obedient Israelites who put the blood on their doors that He would “not suffer the destroyer to come in unto your houses to smite you” (Exodus 12:23For the LORD will pass through to smite the Egyptians; and when he seeth the blood upon the lintel, and on the two side posts, the LORD will pass over the door, and will not suffer the destroyer to come in unto your houses to smite you.
See All...). Paul spoke of the Israelites who murmured in the wilderness and “were destroyed of the destroyer” (1 Corinthians 10:10Neither murmur ye, as some of them also murmured, and were destroyed of the destroyer.
See All...).  The destroyer would probably be one of the angels under the rule of Satan who has power to bring death and destruction.

Some have taught that Revelation 9:11And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.
See All... uses the Hebrew Abaddon to represent the Jews and the Greek Apollyon to represent the Gentiles; showing that both Jew and Gentile will experience the destruction of the locusts. One Bible interpretation identifies Abaddon as Mohammed and the locusts as his devastating armies. John Milton, in Paradise Regained (4.624), uses Abaddon as a name for hell.