'Woe' and 'Alas' signify lamentation over evils and falsities which devastate the church.

In Revelation 18:10, 'alas' signifies lamentation. (Apocalypse Explained 652[18], Apocalypse Explained 654[38])

(Reference: Apocalypse Explained 56; Apocalypse Revealed 416; Revelation 8:13)