Terminology is a polysemous word that can refer to:
a collection of terms belonging to a special subject field;
an activity, i.e. the set of practices and methods used for the collection, description and presentation of terms;
a theory, i.e. the set of premises, arguments and conclusions required for explaining the relationships between concepts and terms which are fundamental for a coherent activity of collecting, describing and presenting terms.
(cf. Sager, A Practical Course in Terminology Processing, 1990, p. 3)
Two Perspectives
From a concept-oriented perspective - taking the concept as initial point - terminology can be defined as:
"A group of concepts of a specialized area and their associated signs" (Felber/Budin, 1989:5).
In contrast, the term-oriented perspective offers defintions such as:
"The items which are characterised by special reference within a discipline are the 'terms' of that discipline, and collectively they form its 'terminology'; those which function in general reference over a variety of sublanguages are simply called 'words', and their totality the 'vocabular'" (Sager, 1990:19).
No matter which perspective is chosen it is important to highlight that both definitions refer to specialised areas and specialised languages (in contrast to common language) and precisely this fact is what sets the limits between terminology and lexicography.