What term is used for a disease that occurs regularly in a population or area?

The term that describes a disease occurring regularly within a specific population or geographic area is "endemic." Endemic diseases are those that are consistently present at a baseline level within a certain region, indicating a stable state of disease occurrence that is expected based on prior experience. This means that the spread of the disease is relatively predictable and maintained within the population over time.

In contrast, "epidemic" refers to a sudden increase in the number of cases of a disease above what is normally expected in that population or area. "Pandemic" signifies an epidemic that has spread over multiple countries or continents, affecting a large number of people. An "outbreak" typically refers to a localized increase in cases of a disease, which can also suggest a sudden rise but is generally used for smaller, more specific instances than an epidemic.

Thus, endemic reflects the regular and predictable presence of a disease, distinguishing it from the other terms that imply unusual patterns of disease occurrence.