A thesaurus is an alphabetical listing of all the subject terms in a single database, used to classify and organize information for that database. The thesaurus shows relationships between terms such as synonymous or related terms, and hierarchical arrangements such as broader terms, or narrower terms. Many subjects also have associated scope notes.

Most ProQuest databases have an associated thesaurus (also called a controlled vocabulary of subject terms).  Editors use the thesauri to assign subject headings to documents in each database.

Using a thesaurus with your search

Click the Thesaurus link located above and to the right of the Advanced Search or Command Line Search forms. A new browser window opens, providing a list of the thesauri titles available for your currently selected databases. 

Click a title to open a thesaurus. You can:

• Search for terms in the thesaurus.
• Browse thesaurus terms, using the alphabetic links.
• Select one or more thesaurus terms, and add them to your search.

By adding thesaurus terms to your search, you can broaden or narrow your search, or find related words to further explore your subject of interest.

You can also combine terms you find in the thesaurus with your current Advanced or Command Line search.

1. Select one or more terms in the thesaurus.
   The number of selected terms displays and updates automatically in a box at the lower left of the Thesaurus window. Click the View link at any time to see your current list of selected terms.
2. If you’ve selected more than one term, specify one of the following operators to join your terms together:
   OR (the default)
   AND
   NOT
3. Click Add to search. Your terms are inserted into the search box where your cursor resides and the Thesaurus window closes.
4. With your terms added to the search form, use an operator to join the terms to the rest of your search.

Important to know — With a particular thesaurus open in the Thesaurus window, you can click this link in the dark blue bar at the top of the window to open a different thesaurus: Select another thesaurus.

Thesaurus tools

For any term you find in the thesaurus, you might see one or more of the following (or similar) bolded words and phrases:

• Use terms/Use term for — synonymous concepts pointing you to authorized terms.
• Use instead — these terms are the preferred thesaurus terms for your search.
• Narrower terms — more restrictive terms associated with a subset of records.
• Broader terms — less restrictive terms associated with a larger set of records.
• Related terms — similar terms suggested for use with your search.
• Scope notes — Scope notes contain information about the use of a subject heading. The scope note may contain a definition of the subject, the year the subject term came into use, and other important information.

Thesauri subject terms with qualifiers

Within the MeSH (MEDLINE) and EMBASE thesauri, you now can view and select qualifiers (narrower terms) associated with subject terms.

"Explode" a search term

The "explode" concept is only available in databases that have a thesaurus. To "explode" a search term means to search a subject term and all its associated narrower terms. Within each thesaurus, you can explode the subject into narrower terms.

Database documents are indexed to the most specific term possible, so by choosing a broad index term, you may not retrieve every document. By using "explode", you can retrieve all documents on a broad topic area.

By exploding a subject term, you search the subject term, and every other term under it in the hierarchy.

"Explode" example

MESH.EXPLODE("diabetes mellitus") will retrieve results for not only the broad subject "diabetes mellitus," but all the narrower terms associated with "diabetes mellitus.”

MESH#("diabetes mellitus") is the short form equivalent of MESH.EXPLODE("diabetes mellitus"); this will retrieve the same results.

MEDLINE and EMBASE support the explode functionality in the Basic, Advanced and Command Line Search for:

• Major MeSH (MJMESH)
• MeSH subjects (MESH)
• EMBASE subjects (EMB)
• Major EMBASE (MJEMB)

You can also search for multiple terms separated by a Boolean operator, for example EMB#("nutrition guidelines" or "myocardial infarction")