Aetiology
Part of speech: noun
Definition: The study of causes or origins. The known or speculated upon origin of a disease or class of diseases, of use in nosology, pathology, and prophylaxis. The ascertained origin of a particular case of a disease. This presumes a diagnosis, and may be relevant to a prognosis, but is distinct from both.
Etiology
Part of speech: noun
Definition: The establishment of a cause, origin, or reason for something.