adj. occurring frequently in a particular region or population: applied to diseases that are generally or constantly found among people in a particular area.
n. a sudden outbreak of infectious disease that spreads rapidly through the population, affecting a large proportion of people.
n. an epidemic so widely spread that vast numbers of people in different countries are affected. The Black Death, the epidemic plague that ravaged Europe in the fourteenth century and killed over one third of the population, was a classical pandemic. AIDS is currently considered to be pandemic.
1. any epidemic disease with a high death rate. 2. an acute epidemic disease of rats and other wild rodents caused by the bacterium Yersinia pestis, which is transmitted to humans by rat fleas. Bubonic plague, the most common form of the disease, has an incubation period of 2–6 days. Headache, fever, weakness, aching limbs, and delirium develop and are followed by acute painful swellings of the lymph nodes (see bubo). In favourable cases the buboes burst after about a week, releasing pus, and then heal. In other cases bleeding under the skin, producing black patches, can lead to ulcers, which may prove fatal (hence the former name Black Death). In the most serious cases bacteria enter the bloodstream (septicaemic plague) or lungs (pneumonic plague); if untreated, these are nearly always fatal. Treatment with tetracycline, streptomycin, and chloramphenicol is effective; vaccination against the disease provides only partial protection.
Definitions are from The Concise Oxford Medical Dictionary, 8th edition, available online via Oxford Reference (accessed October 7, 2014)