A controlled vocabulary is a carefully curated collection of words and phrases relevant to a specific application or industry. Each term in the vocabulary may include additional properties, such as usage behavior and contextual meaning, to ensure consistency and precision in understanding topics and semantics.

While similar to taxonomy in its organizational value, controlled vocabulary differs by focusing on specific words and phrases that need to be identified in a text. In contrast, taxonomy uses nodes as category labels, which do not necessarily represent the actual words or phrases in a document. Controlled vocabularies are essential for ensuring standardized language in data processing and retrieval.