trench 
(trĕnch)
(trĕnch)n.
1. A deep furrow or ditch.
2. A long narrow ditch embanked with its own soil and used for concealment and protection in warfare.
3. A long, steep-sided valley on the ocean floor.
v. trenched, trench·ing, trench·es
v.tr.
1. To dig or make a trench or trenches in (land or an area, for example).
2. To place in a trench: trench a pipeline.
v.intr.
1. To dig a trench or trenches.
2. To encroach. Often used with on or upon: "The bishop exceeded his powers, and trenched on those of the king" (Francis Parkman).
3. To verge or border. Often used with on or upon: "a broad playfulness that trenched on buffoonery" (George Meredith).
[Middle English trenche, from Old French, a cutting, slice, from trenchier, to cut, from Vulgar Latin *trincāre, perhaps partly from Latin *trīncāre, to cut in three (from earlier *trīnicāre : Latin rīnī, three each, triple; see trei- in the Appendix of Indo-European roots + Latin -icāre, as in duplicāre, to double, split in two; see DUPLICATE) and partly from a Gaulish root *trink-, to cut, behead, found in Late Latin trincus trincus, a kind of gladiator who was subject to particular Gaulish customs and probably fought until beheaded (of Gaulish origin, perhaps ultimately from a pre-Roman substrate root *trenk-, to cut, or perhaps akin to Latin truncus, trunk; see terə2 in the Appendix of Indo-European roots).]