When a user performs a basic search in a database, they are using keywords. While keywords are a great way to start a search, a user could also search with terms from a controlled vocabulary.

Controlled vocabularies are standardized, organized sets of terms that databases use to describe content in a consistent fashion. Many databases have their own, unique controlled vocabulary (see table below).

Database Controlled Vocabulary Name Tutorial
CINAHL CINAHL Subject Headings Using CINAHL/MeSH Subject Headings
EMBASE Emtree Searching in Embase
PsycInfo Thesaurus APA Thesaurus of Psychological Index Terms
Pubmed MeSH MeSH in MEDLINE/Pubmed: A Tutorial


Compared to keywords, controlled vocabulary terms usually generate fewer and more relevant results. However, a user must use the exact term. The tutorials in the above table cover how to find and use these terms.

Example situations:

  • If the initial keyword search gave too many or too few results, try controlled vocabulary terms.
  • If a researcher is doing a comprehensive search (e.g. a systematic review), combine both keywords and controlled vocabulary terms to increase the number of resources retrieved.
  • If a user is looking for background information, a keyword search generally suffices.
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