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Searching Tips Guide: Using Textwords, Phrases, Controlled Vocabularies and more

Getting Started

Generally, there are two different techniques you can use for searching an index or database: textwords (or keywords) or controlled vocabulary terms. The type of search terms you use will mainly depend on the database you are using. It is always good to know whether the database uses textword searching, a controlled vocabulary or both. Use the tips below to improve your search techniques!


Textword searching is also known as natural language, free text or keyword searching. Google is a prime example of textword searching. When you search Google, you type in the textwords you want to find and Google will search on these terms. Textword searching does not take into consideration variant spellings (e.g. pediatrics vs. the British paediatrics), nor does it search for synonyms of a search term (e.g. a search done on heart attack will not retrieve articles that use the term myocardial infarction).

In order to perform an effective textword search, incorporate the techniques below.


When searching using textword searching, truncation is an effective means of finding plurals or variants of terms. Truncation allows you to add a symbol to your search term so that all variants of the word appear. The word cell* retrieves articles with the words: cell, cells, cellular, cellulite, cellophane, cellist, and cellphone. With some databases, you can also use truncation in the middle of a term: Wom*n will retrieve women or woman.

Using the Boolean Operator OR

Another technique to keep in mind is to use the Boolean operator OR to link together similar concepts. Use (head injur* OR head trauma OR brain injur* OR brain damage) to find information on head injuries. Entering "like" terms (synonyms) using OR need should be enclosed in parentheses, often called nesting.

For example to retrieve articles discussing head injuries and intracranial pressure, a sample search strategy would look like:

(head injur* OR head trauma OR brain injur* OR brain damage) AND (intracranial pressure OR intracerebral pressure OR subarachnoid pressure)

Phrase Searching

Another technique used for textword searching is phrase searching. Most databases allow you to put your phrase in quotation marks in order to search for the phrase exactly as it appears, an example of this would be fetal alcohol syndrome. Always check to see how the database searched your phrase because it may not recognize the terms as a phrase.

For example, if you enter: health information exchange in PubMed, it runs the search as "health information exchange"[MeSH Terms] OR ("health"[All Fields] AND "information"[All Fields] AND "exchange"[All Fields]) OR "health information exchange"[All Fields].

To force the database to search the entered terms as a phrase, enter them in quotes (single or double quotes depending on the database).

For example, if you enter "health information exchange" in PubMed, it will run your search as "health information exchange"[All Fields].

Always refer to the online help section for specific instruction. See phrase searching details for the following resources:

A controlled vocabulary uses a specific term for a number of synonyms. Once you find the correct term, you do not need to use synonyms in order to perform you search. An example of a source that uses a controlled vocabulary is the yellow pages of the telephone book. Car dealers might be listed under the term automobile dealers. A controlled vocabulary employs a thesaurus, which outlines which term should be used for a concept. For example, MEDLINE employs the MeSH thesaurus (Medical Subject Headings). The MeSH term for breast cancer is breast neoplasms. An article written about breast cancer will be indexed under the term breast neoplasms even if the phrase breast neoplasms is not used by the authors of the article.

A controlled vocabulary allows you more control in choosing search terms. Some techniques that you can use when searching with a controlled vocabulary are outlined below:

Hierarchical structure

  • An advantage to using a controlled vocabulary is the hierarchical nature of the thesaurus. For example, a search for Central Nervous System Diseases would include the term Encephalomyelitis. If I wanted information on central nervous system diseases, including encephalomyelitis, I could search on the broader term. If I wanted information only on encephalomyelitis, I could go directly to the more specific term.

Broader, Narrower and Related Terms

  • Most thesauri include broader terms (BT), narrower terms (NT), and terms that are used for other terms. In addition, sometimes other terms are suggested which might be related. For example, in MeSH, a broader term for Breast Neoplasms is the MeSH term Breast Diseases. A narrower term for Breast Neoplasms is Breast Neoplasms, Male.
  • In addition, a list of terms are included that are all terms that are indexed under Breast Neoplasms they include: Breast Tumor, Tumor, Breast, Neoplasms, Breast, Tumors, Breast and Breast Cancer. The MeSH term Breast Neoplasms does not have any related terms suggested. For additional information on using MeSH, go to the NLM's MeSH Fact Sheet.

Major or Starred Terms

  • Another advantage of using a controlled vocabulary is the ability to designate one or more of your terms as major terms that designate that they are the major topics of the article, usually obtained from the title and/or statement of purpose.

Working Backwards

  • One of the advantages of a controlled vocabulary is that once you find an appropriate item, you can use its record to find other items indexed using the same terms. In the LRC’s catalog, subject terms are listed for each record with active links to those terms. Look in the LRC's online catalog for the book Case Studies in Nursing Ethics. Notice that one of the subject headings that appears at the bottom of the screen is Ethics, Nursing. If you would like to find more books on nursing ethics, click on the subject heading, Ethics, Nursing.

Examples of LRC databases that use a controlled vocabulary:

LRC's Basic Search Instruction Video

Rhonda Allard

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Rhonda J. Allard
James A. Zimble Learning Resource Center • 4301 Jones Bridge Rd. Bethesda, MD 20814 • Main Number: 301-295-3189 • AMI Helpdesk: 301-295-3358

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