Debouch first appeared in English in the 18th century. It derives from a French verb formed from the prefix de- ("from") and the noun "bouche" ("mouth"), which itself derives ultimately from the Latin bucca ("cheek"). "Debouch" is often used in military contexts to refer to the action of troops proceeding from a closed space to an open one. It is also used frequently to refer to the emergence of anything from a mouth, such as water passing through the mouth of a river into an ocean. The word's ancestors have also given us the adjective "buccal" ("of or relating to the mouth") and the noun "embouchure" (the mouthpiece of a musical instrument or the position of the mouth when playing one).