(oceanography) A submarine trench in the North Pacific Ocean, noted for having the deepest known point on Earth.

(uncountable) Warfare in which opposing sides occupy trenches and repeatedly fire at one another; usually involving high casualty rates over a long period of time.

(medicine) An acute infectious disease, caused by the microorganism Rickettsia quintana (now Bartonella quintana) and transmitted by the louse Pediculus humanus, that affected very many soldiers during World War I.

A military-style raincoat with a belt and deep pockets and often epaulettes.

(archaeology) A triangle-shaped cut in a tell, used to see how many levels there are or to find information about each separate settlement.

A medical condition which can affect the feet when they are constantly cold and wet, similar to frostbite.

A pair of binoculars consisting of two periscopes.

plural of trench club

An improvised hand-held weapon used by raiding parties in World War One

The phenomenon of a fire rushing quickly up an inclined surface, due to a combination of the Coandă effect (which causes the fire to hug the inclined surface) and flashover (where the surface of a space near the fire — in this case the surface of the more elevated regions of the incline — is heated until it self-ignites).