onomastics
noun
on·o·mas·tics ˌä-nə-ˈma-stiks 
plural in form but singular or plural in construction
1
a
: the science or study of the origins and forms of words especially as used in a specialized field
b
: the science or study of the origin and forms of proper names of persons or places
2
: the system underlying the formation and use of words especially for proper names or of words used in a specialized field
onomastician
ˌä-nə-ma-ˈsti-shən
noun 
Did you know?
The original word for the science of naming was "onomatology," which was adopted from French in the mid-19th century. About a century later, however, people began referring to the science as "onomastics," a term based on the Greek verb onomazein ("to name"). Like many sciences, onomastics is itself composed of special divisions. An onomastician might, for example, study personal names or place names, names of a specific region or historical period, or even the character names of a particular author, like Charles Dickens.
Word History
First Known Use
1904, in the meaning defined at sense 1a