Emily Dickinson Lexicon

TRENCH, n.

1. A long narrow cut in the earth; a ditch; as, a trench for draining land.
2. In fortification, a deep ditch cut for defense, or to interrupt the approach of an enemy. The wall or breast-work formed by the earth thrown out of the ditch, is also called a trench, as also any raised work formed with bavins, gabions, wool-packs or other solid materials. Hence the phrases, to mount the trenches, to guard the trenches, to clear the trenches, &c. To open the trenches, to begin to dig, or to form the lines of approach.