nosology
noun
no·sol·o·gy nō-ˈsä-lə-jē 
-ˈzä-
-ˈzä- 1
: a classification or list of diseases
2
: a branch of medical science that deals with classification of diseases
nosological
ˌnō-sə-ˈlä-ji-kəl
adjective or nosologic
ˌnō-sə-ˈlä-jik
nosologically
ˌnō-sə-ˈlä-ji-k(ə-)lē
adverb 
Word History
Etymology
borrowed from New Latin nosologia, from Greek nósos "disease" (of obscure origin) + -o- -o- + New Latin -logia -logy
Note: Attic Greek nósos is paralleled by Homeric and Ionic noûsos, suggesting an earlier *noswos, though the Ionic form (chiefly Herodotus) may be taken from Homer; then the possibility arises that noûsos in Homer should have been read *nóssos, in which case *noswos is out of the question. In any event, neither form leads to a plausible etymology.
First Known Use
circa 1721, in the meaning defined at sense 1
Medical Definition
nosology
noun
no·sol·o·gy nō-ˈsäl-ə-jē -ˈzäl-
-ˈzäl- plural nosologies
1
: a classification or list of diseases
2
: a branch of medical science that deals with classification of diseases