—n.
1 a long narrow usu. deep depression or ditch.
2 Mil. a this dug by troops to stand in and be sheltered from enemy fire. b (in pl.) a defensive system of these.
3 a long narrow deep depression in the ocean bed.
—v.
1 tr. dig a trench or trenches in (the ground).
2 tr. turn over the earth of (a field, garden, etc.) by digging a succession of adjoining ditches.
3 intr. (foll. by on, upon) archaic a encroach. b verge or border closely.
Phrases and idioms:
trench coat
1 a soldier's lined or padded waterproof coat.
2 a loose belted raincoat. trench fever a highly infectious disease transmitted by lice, that infested soldiers in the trenches in the war of 1914-18. trench mortar a light simple mortar throwing a bomb from one's own into the enemy trenches. trench warfare hostilities carried on from more or less permanent trenches.
Etymology: ME f. OF trenche (n.) trenchier (v.), ult. f. L truncare TRUNCATE
Useful english dictionary. 2012.