Capitalization When Defining Abbreviations

This tip is a follow-up to our previous discussion of using singular or plural abbreviations. One question we have received on several occasions concerns capitalization of words that define an abbreviation. Because the abbreviation is composed of capital letters, many writers believe that the full words that define the abbreviation should be capitalized as well. Most of the time, the spelled-out words should not be capitalized. Here we have some examples of initialisms and acronyms, which are shortened phrases:

• The program’s graphical user interface was extremely user friendly. The program’s GUI was extremely user friendly.
• Adenosine triphosphate levels strongly affect cytoskeletal rearrangements. ATP levels strongly affect cytoskeletal rearrangements.
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• Polycrystalline platinum is a strong catalyst for decomposing hydrogen peroxide into water and oxygen. Polycrystalline Pt is a strong catalyst for decomposing hydrogen peroxide into water and oxygen.

In certain cases, the words retain a capital letter. Words are capitalized when the abbreviation represents the official name of an organization or company.

• In recent years, the Fédération Internationale de Football Association has struggled with allegations of corruption. In recent years, FIFA has struggled with allegations of corruption.
• Ecuador joined the Organization of the Petroleum Exporting Countries in 2007. Ecuador joined OPEC in 2007.
• The open access journal mBio is published by the American Society for Microbiology. The open access journal mBio is published by ASM.

In addition, proper nouns (the names of specific people, geographical locations, or trademarks) are always capitalized.

• There are four basic properties to each Fourier transform. There are four basic properties to each FT.

We hope that this tip provides some helpful advice for defining abbreviations. As always, please send any questions to [email protected].