A rare zoonotic (animal-borne) viral disease similar to smallpox . The virus responsible for monkeypox is, in fact, related to that responsible for smallpox. Both belong to the orthopox family of viruses. See the entire definition of Monkeypox

Monkeypox is a disease caused by the Monkeypox virus. First identified in 1958 as a pathogen of cynomolgus monkeys, it is an orthopoxvirus with a clinical presentation similar to smallpox.