1.nounAn occurrence of a disease or disorder in a population of non-human animals at a frequency higher than that expected in a given time period. Compare epidemic.
"At the same time as an epidemic of the flu broke out among the people, an epizootic of the swine flu broke out among their pigs."
2.nounA particular epizootic disease.
3.noun(often in the plural) A disease or ailment.
"Johnny's not doing so well today, I think he caught the epizootic."