The word is of Latin origin. It may also be translated as "opening", "air-hole" or "vent".

It is actually one of the two channels of the nose, from the point where they bifurcate to the external opening. Nostrils contain branched bones or cartilages called turbinates. Their main function is to make air warm when you exhale. Everybody knows that fish don't use noses to breathe, but they smell with two small holes, which may, indeed, be called nostrils..