fistula

noun, plural fis·tu·las, fis·tu·lae [fis-choo-lee] /ˈfɪs tʃʊˌli/.

1. Pathology. a narrow passage or duct formed by disease or injury, as one leading from an abscess to a free surface, or from one cavity to another.
2. Surgery. an opening made into a hollow organ, as the bladder or eyeball, for drainage.
3. Veterinary Pathology. any of various suppurative inflammations, as in the withers of a horse (fistulous withers), characterized by the formation of passages or sinuses through the tissues and to the surface of the skin.
4. Obsolete. a pipe, as a flute.

noun plural -las or -lae (-ˌliː)

1. pathol an abnormal opening between one hollow organ and another or between a hollow organ and the surface of the skin, caused by ulceration, congenital malformation, etc
2. obsolete any musical wind instrument; a pipe

n. pl. fis•tu•las

1. An abnormal passage from a hollow organ to the body surface, or from one organ to another.