The study of disease, including causes, development and effects on the body.
The symptoms, processes or conditions of a disease.
A doctor who specializes in the causes and nature of disease is called a pathologist. Pathologists help determine diagnosis, prognosis and treatment by studying cells and tissues under a microscope and using laboratory tests.
Pathological means referring to or having to do with pathology. It can also refer to something related to or caused by a disease, as in pathological fracture.