What term describes a tract leading from a point of infection to a point of eruption outside the body?

The term that describes a tract leading from a point of infection to a point of eruption outside the body is known as a fistula. A fistula is an abnormal connection or passageway that forms between two organs or vessels that do not normally connect. In the context of an infection, it may develop as a conduit for pus or fluid to drain from an abscess or infected area to the surface of the skin, facilitating the expulsion of infectious material and relieving pressure.

In contrast, an abscess pertains to a localized collection of pus within tissue due to infection or inflammation, typically presenting as a swollen area. An ulcer represents a break in the skin or mucous membrane that fails to heal, featuring tissue loss generally associated with underlying trauma, disease, or infection. A granuloma is a small area of inflammation characterized by the presence of macrophages and is often related to chronic inflammatory conditions, but it doesn't form a tract like a fistula. Thus, the characteristics of a fistula specifically match the description given in the question.