A disease that is constantly present to a greater or lesser degree in people of a certain class or in people living in a particular location WordNet 3.0 & Open English WordNet

In epidemiology, an infection is said to be endemic in a specific population or populated place when that infection is constantly present, or maintained at a baseline level, without extra infections being brought into the group as a result of travel or similar means. Wikipedia

Epidemiological term describing a disease which is constantly present in a specific area Wikidata

A disease affecting a number of people simultaneously, so as to show a distinct connection with certain localities. Wiktionary

Disease affecting a number of people simultaneously, so as to show a distinct connection with certain localities. Wiktionary (translation)