OED: 1. The assignment of a cause, the rendering of a reason; also, the reason annexed, the wherefore of a command or utterance.
2. The science or philosophy of causation; that part of philosophy which treats of the demonstration of causes; the part of any special science which speculates on the causes of its phenomena.
3. That branch of medical science which investigates the causes and origin of diseases; the scientific exposition of the origin of any disease.
(OED, 2nd Ed, accessed through U of MN Libraries)
Taubes’ “Response”: “Significant fat loss on carbohydrate-restricted diets, unrestricted in calories, is the kind of paradoxical observation that might actually inform our understanding of the true aetiology of the disorder itself.”
Sentence: The scientist conducted interviews to learn more about the aetiology of the epidemic.