EPIDEMIC

n. outbreak, plague, something which spreads quickly (i.e. a disease)

adj. (about a disease) affecting many people at once; widespread, very common

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 experience (the number of new cases in the population during a specified period of time is called the "incidence rate"). (An epizootic is the same thing but for an animal population.)
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Epidemic! is a real-time strategy game in which the player stands in control of a world on the brink of extinction. A space-borne plague has hit the planet and the player must stem the epidemic as quickly as possible and with minimal loss of life.Developed solely by Steven Faber in machine code, this game was created for Strategic Simulations, Inc. Your range of methods to deal with the epidemic range from inert methods like interferon, to quarantine, to the ultimate in immediate cessation, strategical nukes.
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Epidemic /ep·i·dem·ic/ occurring suddenly in numbers clearly in excess of normal expectancy. ep·i·dem·ic or ep·i·dem·i·cal adj. [more]Epidemic - Community and Resources

Noun
1. a widespread outbreak of an infectious disease; many people are infected at the same time
(hypernym) outbreak, eruption, irruption
(hyponym) pandemic
Adjective
1. (especially of medicine) of disease or anything resembling a disease; attacking or affecting many individuals in a community or a population simultaneously; "an epidemic outbreak of influenza"
(antonym) endemic, endemical
(similar) pandemic
(classification) medicine, medical specialty

(n.)
Anything which takes possession of the minds of people as an epidemic does of their bodies; as, an epidemic of terror.
  

(n.)
An epidemic disease.
  

(a.)
Alt. of Epidemical