Set of technical words or expressions used in a particular subject
Source: Oxford Dictionary.
Introduction to the notion
According to the Enterprise System Topology, terminology is part of the intentional aspect.
The Enterprise Terminology is a set of terms with their definitions and relations, coping with all the situations we encounter in clarifying the business language, especially at a worldwide scale (synonyms, homonyms, ambiguities, various references and background).
From a business perspective, benefits include common understanding, ability for comparing practices, leveraging group scale.
In another meaning, terminology also is the discipline or science that studies the vocabulary.