WordNet
n. a knife with a double-edged blade for hand-to-hand fighting
Wikipedia
A trench knife is a combat knife designed to kill or gravely incapacitate an enemy soldier at close quarters, as might be encountered in a trenchline or other confined area. It was developed in response to a need for a close combat weapon for soldiers conducting assaults and raids on enemy trenchlines during the First World War. An example of a World War I trench knife is the German Army's Nahkampfmesser (close combat knife).
With the outbreak of the Second World War, the trench knife, by this time usually referred to as a combat knife, proved so useful that armies continued to develop and issue new designs. On the Axis side, the Nahkampfmesser and designs developed from it were again widely issued to the ordinary soldier as general-purpose fighting and utility knives, while Allied armies generally restricted issue of trench knives to elite infantry units and infantry not otherwise equipped with the bayonet.
Usage examples of "trench knife".
In his musette bag he had two grenades and a demolitions kit, plus his trench knife.
I took my trench knife from my boot and cut myself out of the harness.
Craig reared back to butt him again, but the Shana shifted over him and suddenly he had the trench knife out of its scabbard on his belt.
Taking his trench knife, a relic of WWI with a foot-long blade and brass knuckles on the grip, he began cutting down shrubbery and branches to conceal the Chevy.
He wore a pistol on his belt and a heavy trench knife was slung in a holster on his left breast.
It was a lot better than the rest of the issue crap: a stupid little ice axe thing and a trench knife you couldn't slice baloney with.
Now, lying in the ditch with Billy and the scouts after having been shot at, Weary made Billy take a very close look at his trench knife.
He marveled at Weary's cruel trench knife, said in German that Weary would no doubt like to use the knife on him, to tear his face off with the spiked knuckles, to stick the blade into his belly or throat.