Keywords and Controlled Vocabulary Terms
Southcentral Kentucky Community and Technical College Library

Keywords and Controlled Vocabulary Terms

library book.jpg Students should begin a research project by first locating background information about the topic. This helps students develop the research question from a broad topic to a focused question.

The next step is to identify keywords, terminology, and synonyms to be used in their research.


keywords.jpg Keyword is the most popular search option. A keyword search looks for ANY occurrence of the term.

In a library catalog, keyword search will look for occurrences of the term or terms in every field (For example: Author field, Title field or Subject field).

In library databases, keyword search can search for occurrences of the term or terms in every field or throughout the text of an article.


How to Build a Keyword List

Following are effective strategies for building a list of search terms:

For more information on identifying search terms, see the SKYCTC Library Tutorial: Search Strategies.


Some content, images and activities were inspired by, and/or copied/adapted from IRIS-42 ( ) which is an Information Literacy project developed with a grant from the Distance Learning Council of Washington, 2007-2008. Some content, images and activities for IRIS-42 were inspired by, and/or copied/adapted from TILT: The Texas Information Literacy Tutorial. This material may be distributed only subject to the terms and conditions set forth in the TILT Open Publication License (the latest version:


Controlled Vocabulary

LC Subject headings.jpg The materials in the SKYCTC Library are catalogued using the Library of Congress Classification System. This system uses controlled vocabulary or subject headings established by the Library of Congress Subject Headings to describe what the item is about.

Subject headings are located in the subject field in the catalog description of an item and can be used to narrow or broaden your search results.


How to Use Subject Headings

We tend to use natural language when we begin a search. For instance, if you wanted to know what books the library had on vegetarian cooking, you would probably type vegetarian cooking in the search box and search by keyword.


How to Use Subject Headings

The catalog search will list titles of books that include either the keywords 'vegetarian' or 'cooking' or both. This means that you will get many titles about cooking but not necessarily items about vegetarian cooking. So how can we use subject headings to narrow our search and avoid looking through a long list of titles?

Click on a title in the catalog search that appears to be specifically on vegetarian cooking.



How to Use Subject Headings

Each item in the catalog will have a subject field: Subjects. This field represents the Library of Congress Subject Headings and gives you the controlled vocabulary used for this subject. The subject headings listed for any item are all active links. In this example, students would click on the link 'Vegetarain cooking' in order to narrow the focus of the catalog search for items on your topic.




How to Use Subject Headings

The catalog search now lists only books that have the subject heading 'vegetarian cooking'.


Keyword vs. Subject Searching

Searching by subject headings is often the most effective and precise way to search periodical databases. However, keyword searching has its benefits too. Listed in the table below are some key points about each:



  • natural language words describing your topic - good to start with
  • pre-defined "controlled vocabulary" words used to describe the content of each item (book, journal article) in a database
  • more flexible to search by - can combine together in many ways
  • less flexible to search by - need to know the exact controlled vocabulary term
  • database looks for keywords anywhere in the record - not necessarily connected together
  • database looks for subjects only in the subject heading or descriptor field, where the most relevant words appear
  • may yield too many or too few results
  • if too many results - also uses subheadings to focus on one aspect of the broader subject
  • may yield many irrelevant results
  • results usually very relevant to the topic

The table is from MIT Libraries Information Navigator web site.

Expand Your Search Terms


thesaurus.jpg Synonyms are words that have the same meaning, for example "car" and "automobile". Using synonyms as alternative keywords will help you expand your search. Try using a thesarus. A thesaurus is a list of synonyms and can help you identify some alternative keywords.

Online sources:


Expand Your Search Terms


acronyms.jpg An acronym is a word or abbreviation formed from the initial letters of the several words in the name. Some examples of acronyms are:

Use the Acronym Finder to determine the words for an acronym:

Librarian's Tip

librarian_1.jpg In order to capture all the information on your topic be sure to use the acronym in addition to the phrase or name. For example, if you were doing research on the effect of ADHD on learning for elementary school-aged children, an effective search would be to use both the name "Attention Deficit Hyperactivity Disorder" and the acronym "ADHD".

The Successful Research Process

Research is always a multistep process but the time a student researcher puts into it will pay off in the end.

It is helpful to understand how the terms you use can narrow or expand your search results.

Need help deciding on what terms or phrases to use in your library catalog, database or Internet search?
Contact the Help Desk at 270-901-1026.


If you require a Certificate of Completion for your instructor, complete the following: