the science of defining the technical or special terms of a particular subject or field of study.
Origin: 1810–20; < Gk horism(ós) definition, lit, marking of boundaries (deriv. of horízein to delimit, make a boundary; see horizon) + -o-+ -logy, with erroneous omission of initial h-
[awr-iz-mol-uh-jee, or-] 
ɪzˈmɒl