Editing Tip: Singular and Plural Abbreviations

Because of the complexity of academic writing, the use of acronyms or abbreviations is often necessary. Abbreviations can clarify text by providing a shortened “code” for a longer string of words, but there is some confusion about how to use abbreviations appropriately. Can abbreviations be pluralized? What if the abbreviation already stands for something plural or the final word has an irregular plural form?

Basic rules of abbreviations and acronyms

Abbreviations and acronyms are shortened forms of names. They are typically portrayed as capital letters of the first letter of each word in the name or phrase, but there are always exceptions. For example, "DNA" is an abbreviation for a two-word phrase (deoxyribonucleic acid) and TB stands for one word (tuberculosis).

Punctuation

Punctuation depends on the style guidelines you're using. Some will allow periods between each letter, but that is less common. An apostrophe is not necessary before the 's' in plural abbreviations and plural acronyms.

Some commonly used abbreviations

• TBD: To be determined
• PIN: Personal Identification Number
• ZIP: Zone Improvement Plan
• CNS: Central Nervous System
• ICU: Intensive Care Unit

Abbreviations vs. acronyms

All acronyms are abbreviations, but not all abbreviations are acronyms. An acronym is an abbreviation that is pronounced as a word. For example, NASA is an acronym for National Aeronautics and Space Administration; people usually just say “NASA” instead of the long form.

Examples of singular and plural abbreviations

Examples of singular and plural abbreviations

Regarding pluralization, abbreviations should reflect the meaning you wish to convey. If you are referring to a plural object, then a plural form with an 's' is appropriate (e.g., EKGs for electrocardiograms). When you have questions about how to form an abbreviation, remember this general rule: read the sentence as though the abbreviation were written out fully. We have provided examples of how to use the following initialisms and acronyms, which are shortened phrases:

Example 1

• Dendritic cells (DCs) are important antigen-presenting cells. Each DC is loaded with MHC class II molecules that allow it to display antigens to other immune cells such as T-cells.

Here, the original abbreviation is pluralized to reflect the discussion of 'dendritic cells' as a plural subject. The second sentence, however, uses the singular abbreviation form (DC) because the sentence should describe 'each dendritic cell' NOT 'each dendritic cells.'

Example 2

• Many factors are required for DC activation.

Again, reading the sentence with the term fully defined will show why 'DC' is the correct choice here. In English, plural nouns cannot be used as adjectives. Therefore, 'dendritic cell activation' is correct (NOT 'dendritic cells activation'), even though many dendritic cells can be activated during an infection.

Please note that it would be acceptable to write "Many factors are required for the activation of DCs." Describing the activation of dendritic cells is grammatically correct. In this case, the term 'dendritic cells' is no longer functioning as an adjective.

Example 3

• The hydroxyl radical, a potent reactive oxygen species (ROS), reacts quickly with other molecules to achieve a stable electron configuration. Various ROS are produced during normal cellular activities.

In these examples, the final term ('species') can be singular or plural. Therefore, the abbreviation ROS can act singular ("a potent ROS") or plural ("Various ROS are"). Because the term does not change when pluralized, the abbreviation does not require an additional 's' at any point (i.e., not 'ROSs').

Example 4

Things get a little trickier when the abbreviation includes a term that is pluralized in an irregular way. For example, the suprachiasmatic nucleus, a portion of the brain near the midline, is commonly abbreviated SCN. This abbreviation is used normally when referring to a single nucleus:

• The SCN is comprised of a network of thousands of heterogeneous neurons. (Hu et al., 2012)

The plural form of 'nucleus' is 'nuclei,' which does not contain an 's' at the end. However, by convention, the abbreviation SCN can be pluralized with an 's' (to SCNs) when referring to multiple nuclei. In this case, although the 's' is not present in the plural term 'nuclei,' the presence of the 's' signifies to the reader that the abbreviation is meant to be plural:

• [W]e analyzed [multi-unit neural activity] of the SCNs of 15 adult C57BL6 mice. (Hu et al., 2012).
• Note: this should be read as 'we analyzed multi-unit neural activity of the suprachiasmatic nuclei of 15 adult mice.'

We hope that this post will help you the next time you need to use an abbreviation in your writing. If you have questions about any particular abbreviation, please write to [email protected]. Thanks!