1. An infectious disease in humans caused by some species of bacteria of the genus Brucella, that is transmitted by contact with infected animals or raw milk products and marked by fever, malaise, severe headache, and joint pain. Also called Gibraltar fever, Malta fever, Mediterranean fever, undulant fever.

2. An infectious disease chiefly of domestic animals, such as cattle, sheep, goats, and dogs, that is caused by some species of bacteria of the genus Brucella, and sometimes results in spontaneous abortions in newly infected animals. Also called Bang's disease.