What is Pathology?

Legal Definition
Pathology (from the Greek roots of pathos (πάθος), meaning "experience" or "suffering", and -logia (-λογία), "study of") is a significant component of the causal study of disease and a major field in modern medicine and diagnosis.

The term pathology itself may be used broadly to refer to the study of disease in general, incorporating a wide range of bioscience research fields and medical practices (including plant pathology and veterinary pathology), or more narrowly to describe work within the contemporary medical field of "general pathology," which includes a number of distinct but inter-related medical specialties that diagnose disease—mostly through analysis of tissue, cell, and body fluid samples. Used as a count noun, "a pathology" (plural, "pathologies") can also refer to the predicted or actual progression of particular diseases (as in the statement "the many different forms of cancer have diverse pathologies"), and the affix path is sometimes used to indicate a state of disease in cases of both physical ailment (as in cardiomyopathy) and psychological conditions (such as psychopathy). Similarly, a pathological condition is one caused by disease, rather than occurring physiologically. A physician practicing pathology is called a pathologist.

As a field of general inquiry and research, pathology addresses four components of disease: cause/etiology, mechanisms of development (pathogenesis), structural alterations of cells (morphologic changes), and the consequences of changes (clinical manifestations). In common medical practice, general pathology is mostly concerned with analyzing known clinical abnormalities that are markers or precursors for both infectious and non-infectious disease and is conducted by experts in one of two major specialties, anatomical pathology and clinical pathology. Further divisions in specialty exist on the basis of the involved sample types (comparing, for example, cytopathology, hematopathology, and histopathology), organs (as in renal pathology), and physiological systems (oral pathology), as well as on the basis of the focus of the examination (as with forensic pathology).

The sense of the word pathology as a synonym of disease or pathosis is very common in health care. The persistence of this usage despite attempted proscription is discussed elsewhere.
-- Wikipedia
Legal Definition
Med. jur. The science or doctrine of diseases. In cases of homicides, abortions, and the like, it is of great consequence to the legal practitioner to be acquainted, in some degree, with pathology. 2 Chit. Pr. 42, note.
-- Bouviers Law Dictionary
Legal Definition
In medical jurisprudence. The science or doctrine of diseases. That part of medicine which explains the nature of diseases, their causes, and their symptoms. See Bacon v. U. S. Mut. Acc. Assin, 123 N. Y. 304, 25 N. E. 399, 9 L. B. A. 617, 20 Am. St. Rep. 748.
-- Black's Law Dictionary