opening made into a hollow organ, as the bladder or eyeball, for drainage
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
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
an abnormal passage that leads from an abscess or hollow organ or part to the body surface or from one hollow organ or part to another and that may be surgically created to permit passage of fluids or secretions
a duct formed by the imperfect closing of a wound [n FISTULAE, FISTULAS] : FISTULAR [adj]