Webster's Revised Unabridged Dictionary · 1913

Abaddon

Abaddon (ȧ*bad"dun) , noun

[Hebrew ābaddōn destruction, abyss, from ābad to be lost, to perish.]

1.
The destroyer, or angel of the bottomless pit; -- the same as Apollyon and Asmodeus.
2.
Hell; the bottomless pit. [Poetic]
In all her gates, Abaddon rues Thy bold attempt. — Milton