In epidemiology, an epidemic (from Greek epi- upon + demos people) is a classification of a disease that appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is "expected," based on recent...

endemism, an organism being "endemic" means exclusively native to a place or biota

endemic (epidemiology), an infection is said to be "endemic" in a population when that infection is maintained in the population without the need for external inputs.

Endemic, in a broad sense, can mean "belonging" or "native to", "characteristic of", or "prevalent in" a particular geography, race, field, area, or environment; native to an area or scope. It also has two specific meanings: