In the page on Field Searching, we mentioned that you can search for your terms in the subject field to get more targeted results.

In some databases, you can take this further by utilising the database thesaurus.

Image: The thesaurus screen in the ERIC database (EBSCOhost).

What is a thesaurus?

In the Library context, a thesaurus is an organised system of subject headings/terms in a database where:

• the database is subject-specific, and therefore the headings/terms are subject-specific
• you can browse and search in the thesaurus for terms to use in your search
• the subject terms are assigned according to article content, allowing you to create a more targeted and effective search
• the subject terms are usually organised hierarchically
• there are usually added features that allow for sophisticated searching.
   

Not all databases have a thesaurus

To identify whether the database you are using has a thesaurus, look for a heading or tab at the top of the search screen. It might be labelled Thesaurus, or it might have a specific name such as CINAHL Subject Headings or MeSH Terms.
 

How do I use a thesaurus?

This will vary according to the database. The process is usually to browse or search the thesaurus to identify the subject term which matches your topic, and then add that term (or terms) into a search box or search builder. When using a thesaurus, we usually search for one concept, or part of a topic, at a time, and then use Search History to combine the search sets.

Some databases/thesauri have extra features which might include:

• a tick-box for Suggest subject terms (EBSCOhost) or Map term to subject heading (Ovid) where the database attempts to match your term to a thesaurus term
• scope notes for each subject term which describe what they are used for
• a set of sub-headings which can also be used in your search
• a hierarchical arrangement where you can identify broader and narrower terms (different from sub-headings)
• the capacity to "explode" a subject search to return narrower terms as well
• suggested related terms
• a system of major and minor subject headings where you can search for your term only as a major heading.