TBESG
Ἀβαδδών (Heb. אֲבַדּוֹן, destruction; LXX, ἀπώλεια, only in Wisdom Lit., of the place of the ruined dead: Job.26:6, 28:22, 31:12, Psa.88:12, Pro.15:11*), indecl.;
in NT, Abaddon, the angel of the Abyss: Rev.9:11.† (AS)
Translators Brief lexicon of Extended Strongs for Greek based on Abbot-Smith, A Manual Greek Lexicon of the New Testament (1922) (=AS), with corrections and adapted by Tyndale Scholars