Common to many people. An epidemic disease is one which seizes a great number of people, at the same time, or in the same season. Thus we speak of epidemic measles; epidemic fever; epidemic catarrh. It is used in distinction from endemic or local. Intemperate persons have every thing to fear from an epidemic influenza.

Generally prevailing; affecting great numbers; as epidemic rage; an epidemic evil.

A popular disease; a disease generally prevailing. The influenza of October and November 1789, that of March and April 1790, that of the winter 1824-25, and of 1825-26, were very severe epidemics.