French épidémique, from Middle French, from epidemie, noun, epidemic, from Late Latin epidemia, from Greek epidēmia visit, epidemic, from epidēmos visiting, epidemic, from epi- + dēmos people — more at demagogue
- 1: affecting or tending to affect a disproportionately large number of individuals within a population, community, or region at the same time <typhoid was epidemic>
- 2a : excessively prevalent
- b : contagious 4 <epidemic laughter>
- 3: characterized by very widespread growth or extent : of, relating to, or constituting an epidemic <the practice had reached epidemic proportions>
In epidemiology, an epidemic (επι (epi)- meaning "upon or above" and δεμος (demos)- meaning "people"), occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience. The disease is not required to be communicable. An epidemic may be restricted to one locale, or it may be global, in which case it is called a pandemic. A few cases of a very rare disease may be classified as an epidemic, while many cases of a common disease (such as the common cold) would not.