Terminology (12)
I believe the answer is:
nomenclature
'terminology' is the definition.
(I know that terminology can be written as nomenclature)
This is all the clue.
(Other definitions for nomenclature that I've seen before include "System involving naming" , "list of names" , "Neater column (anag) - terminology" , "Classified system of names" , "Particular terminology - near Uncle Tom (anag)" .)