The first breaking of ground by besiegers, in order to carry on their approaches towards a besieged place.
·p.pr. & ·vb.n. of <<Open>>. II. Opening ·noun Hence: A vacant place; an opportunity; as, an openin...
Webster's Dictionary of the English Language
The earthworks by which a besieger approaches a fortified place; generally half sunk in the ground, ...
The Sailor's Word-Book
See counter-approaches. ...