1.nounA treatise or written classification of diseases.
2.nounThe study of diseases; the systematic investigation or classification of disease.
3.nounThe characteristics or scientific understanding of a specific disease.
"2003: Thomas Arnold [...] constructed a nosology of insanity explicitly on the basis of the Lockean philosophy of mind — Roy Porter, Flesh in the Age of Reason (Penguin 2004, p. 312)"