Merriam-Webster's Collegiate® Dictionary, 11th Edition
TRENCH
I. noun see: trine
Date: 15th century
1. a long cut in the ground ; ditch , a place, position, or level at which an activity is carried on in a manner likened to trench warfare, a long, narrow, and usually steep-sided depression in the ocean floor, trench coat ,
II. verb
Date: 15th century
transitive verb to make a cut in ; carve ,
2. to protect with or as if with a trench, to cut a trench in ; ditch , intransitive verb
1. entrench , encroach , to come close ; verge , to dig a trench