A long-term illness or condition. In medicine, a chronic disease is a disease that is sustained or reoccurring. The term chronic outlines the evolution of the disease, or its rate of onset and development. A chronic course is defined differently from a recurrent course; recurrent diseases repeat, with periods of absence. Chronic can also refer to a persistent and enduring medical condition. Chronicity is generally applied to an illness that lasts more than two or three months.

See also:
Pandemic
Disease awareness marketing