DEFILE  , a military expression for a passage, to

march through which troops are compelled to " defile," or narrow their front (from the Fr. defiler, to march in a line, or by" files ") . The word is usually applied to a ravine or gorge in a range of hills, but a causeway over a river, a bridge and even a village may equally be called a defile . The term is also used to express, without any special reference to military operations, a gorge in mountains . The verb " to defile " is used of troops marching on a narrow front, or narrowing their front, under all circumstances, and in this sense is the contrary of " deploy." "Defile," in the sense of "pollute," is another form of " defoul "; though spelt alike, the two words are pronounced differently, the accent being on the first syllable for the former and on the second for the latter .