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Natural language is another way to say keywords. When we are searching with keywords, we are using the language that is commonly used to describe things. Searching with keywords expands the search because you can include synonymous or narrower terms for broad concepts. You can also specify what fields to search using your keyword(s). 

Since keywords have a wide variation due to different spellings of the same word, multiple synonyms for a single concept, and acronyms for concepts; generating keywords can be a lengthy process.

Generating Keywords

Determine what synonyms are true to the concepts in the research question. 

Are anti-smoking campaigns effective interventions for e-cigarette use among high school students?

Keywords listed here are not exhaustive 

Concept 1: anti-smoking campaigns

Some keywords may include:

  • anti-smoking campaigns
  • antismoking campaigns
  • anti-vaping campaigns
  • antivaping campaigns 
Keyword terms can have different morphological forms for the same word, such as alternative spellings. Here the hyphenated (anti-smoking campaigns and anti-vaping campaigns) and unhyphenated (antismoking campaigns and antivaping campaigns) would be used in a search because the database distinguishes between the two. 

Concept 2: e-cigarette

Some keywords may include:

  • e-cig*
  • ecig*
  • electronic cigarette*
  • vap*
Concept 2 displays morphological variation for the e-cigarettes concept similar to Concept 1. The asterisk is used in most database for truncation. Electronic cigarette* is also used to search because it is a true synonym of the concept. Use both acronyms, abbreviations, and the fully spelled out versions of keyword terms for searching. 

Concept 3: high school students

Some keywords may include: 

  • high school student*
  • adolescent*
  • minors 
  • teen*

Sometimes keywords may not look anything like the concept. However, those keywords listed here are true synonyms of the concept. High school students typically are in the age range between 14-18 years old. In this age range, they are legally-speaking minors. The last keyword, teen*, has an asterisk like keywords in concept 2 for truncation. The database will also retrieve results with teens and teenagers. 



What is truncation?

Truncation should be used to search within a database because it accounts for word variability. It typically requires the use of a symbol to represent variation in word endings. For example in Concept 3, the keyword teen* is truncated at the end with an asterisk (*) to search for the terms: teen, teens, teenager, and teenagers. To truncate a word place the symbol where the word begins to change to account for various word endings. Truncation symbols can vary across databases. 

Subject Headings vs. Keywords

Subject headings

  • Typically assigned by a person
  • Come from a designated vocabulary called a subject headings list or controlled vocabulary
  • Indexed within their own designated field in the resource's record 


  • Searches for your term anywhere in the record
  • Not as precise as subject headings
    • (e.g. an article may mention that keyword once throughout the whole paper, but that paper may not have anything to do with that keyword)
  • Uses natural language