orismology
noun
or·is·mol·o·gy ˌȯr-əz-ˈmä-lə-jē 
ˌär-
: the science of defining technical terms
orismological
ˌȯr-əz-mə-ˈlä-ji-kəl
adjective ˌär-;
ȯ-ˌriz-
Word History
Etymology
Greek horismos definition (from horizein to define) + English -logy — more at horizon
First Known Use
1815, in the meaning defined above