trench (n.) Look up trench at Dictionary.com
late 14c., "track cut through a wood," later "long, narrow ditch" (late 15c.), from Old French trenche "a slice, cut, gash, slash; defensive ditch" (13c., Modern French tranche), from trenchier "to cut, carve, slice," possibly from Vulgar Latin *trincare, from Latin truncare "to cut or lop off" (see truncate). Trenches for military protection are first so called c.1500. Trench warfare first attested 1918. Trench-coat first recorded 1916, a type of coat worn by British officers in the trenches during World War I.