NOSOL'OGY, noun [Gr. disease, and discourse.] 1. A treatise on diseases, or a systematic arrangement or classification of diseases with names and definitions, according to the distinctive character of each class, order, genus and species. 2. That branch of medical science which treats of the classification of diseases.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI