Merriam-Webster Collegiate Dictionary - epidemic

 I. adjective  Etymology: French epidemique, from Middle French, from epidemie, noun, ~, from Late Latin epidemia, from Greek epidemia visit, ~, from epidemos visiting, ~, from epi- + demos people — more at demagogue  Date: 1603  1. affecting or tending to affect a disproportionately large number of individuals within a population, community, or region at the same time typhoid was ~  2.  a. excessively prevalent  b. contagious 4 ~ laughter  3. of, relating to, or constituting an ~ the practice had reached ~ proportions  • ~al adjective  • ~ally adverb  • ~ity noun  II. noun  Date: 1757  1. an outbreak of ~ disease  2. an outbreak or product of sudden rapid spread, growth, or development an ~ of bankruptcies