Skip to Main Content
Library Hours

Evidence-Based Practice

Brainstorming Search Terms

Before you begin to search in the databases, you want to spend some time thinking about what terms you will use in your search.

There are two main types of search terms: Subject Headings and Keywords

Using a combination of keywords and subject headings will create a stronger search.

Search Term Development

When searching the literature, you want to make sure you are searching for all the possible variations and different words that could be used to describe your topic.  For example, using both the terms cavities and dental caries.

  • Use the concepts you identified in your PICO question to help brainstorm search terms for your search.


  • Determine which concepts are primary concepts (i.e. which concepts are the most important).  Depending on your topic, you may not need search terms for every concept.


  • For each primary concept, think of as many different ways to describe the concept as you can.

PICO Keyword Chart

Synonyms are an important part of developing a thorough search strategy.

Subject Headings & Keywords

What is a Subject Heading?

Each database will have its own special set of terms or subject headings that the indexers use to describe articles. 

When developing your search strategy, it is always a good idea to take a look at the subject headings for that database to ensure you are using the official term, as well as to get ideas for synonyms or alternative search terms to use. 

Below are descriptions of some of the commonly used subject headings.

  • Used by the National Library of Medicine to index MEDLINE/PubMed, MeSH stands for Medical Subject Headings.  
  • MeSH terms are organized in a tree structure that moves from more general to more specific. 
  • Each term will have "Entry Terms", which are synonyms that PubMed will automatically map to the MeSH term when searched. 
  • To search the MeSH database, select MeSH from the drop down menu next to the search box, or select MeSH Database under More Resources on the PubMed homepage. 


CINAHL Headings
  • These are the subject headings used within the CINAHL database. 
  • They are often the same as the MeSH term used in PubMed, but they can be different. 
  • To access the CINAHL Headings, click the link at the top of the database screen. 
  • If you are searching more than one Ebsco database, you can hover your mouse over Subjects, then select CINAHL Headings from the list.


  • The database Embase uses their own subject headings called Emtree. 
  • These terms are also organized in a tree structure and have many synonyms included in the entry. 
  • The Emtree terms often differ from the MeSH terms (e.g. they use natural language, instead of inversion), but the corresponding MeSH term is typically mapped to the Emtree term as a synonym. 
  • To search for terms in Emtree, click on the Emtree link at the top of the Embase search screen.  Embase will also typically suggest the Emtree term as you type keywords into the search box. 

What is a Keyword?

In addition to searching with subject headings, you want to also include any synonym or similar keywords in your search.  These are the terms that you might see in the titles and abstracts of the articles.

This is important to catch any results that may have been indexed with a different subject heading than you would expect.

In some databases, it will also help catch results that may not have been fully indexed yet (this is especially important in PubMed).

  • Different people can use different words to describe the same thing. 
  • In searching, keywords can be any word or acronym that is used to describe a concept or idea. 
  • Common variations can include spelling (pediatric vs paediatric), abbreviations (left ventricular assist device vs LVAD), technical/medical terminology (heart attack vs myocardial infarction), and synonyms (teenager vs adolescent).