Final answer:
An epidemic is the occurrence of a disease in excess of what is normally expected. It refers to a disease that occurs in an unusually high number of individuals in a population at the same time.
Step-by-step explanation:
An epidemic is defined as the occurrence of a disease in excess of what is normally expected. It refers to a disease that occurs in an unusually high number of individuals in a population at the same time. For example, when there is a sudden increase in the number of flu cases in a specific region during the winter, it would be considered an epidemic.