病理学为医学领域的一门分支学科，专门探讨疾病在个体发生的起因、发展及变化，以及整个过程对患者产生的各种影响。此学科在医学教育中属于基础学群；临床操作利用病理学知识分析采样检体，以辅助医师诊断和处方；研究层级则试图解释疾病造成生理变化的未明现象。因此该学科在医院被称为「医生中的医生」（Doctor's Doctor）。

病理学是研究疾病发生发展规律，阐明疾病本质的一门医学基础学科，是医学科学实践的基础。病理学的主要任务是研究疾病发生的原因、发病机制，以及疾病过程中患病机体的形态结构、功能代谢改变与疾病转归，从而为疾病的诊断、治疗、预防提供必要的理论基础和实践依据。

Pathology (from the Ancient 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.