All about Abbreviations in Academic Writing: A Guide

Abbreviations save space and prevent repetition, but they create problems when used inconsistently. A manuscript that defines “SEM” as “structural equation modelling” on page 3 and then uses it without definition on page 12, or one that introduces 15 abbreviations in the first paragraph and expects the reader to remember all of them, is harder to read than a manuscript that uses no abbreviations at all.

This guide covers the rules for using abbreviations correctly in academic writing, the common mistakes to avoid, and the conventions that differ between style guides.

The Basic Rule: Define on First Use

Every abbreviation must be defined on first use. Write the full term first, followed by the abbreviation in parentheses. After that, use only the abbreviation.

“The participants completed the Beck Depression Inventory (BDI). Scores on the BDI ranged from 0 to 63.”

Do not reverse the order. “The BDI (Beck Depression Inventory)” is incorrect. The reader encounters the abbreviation before they know what it stands for.

Universally known abbreviations in your field may not need definition. DNA, MRI, GDP, and HIV are examples. However, “universally known” is a high bar. If your paper might be read by researchers outside your immediate subfield, define the term. When in doubt, define it.

Only Abbreviate Terms Used Three or More Times

If a term appears only once or twice in your manuscript, do not abbreviate it. The reader gains nothing from memorising an abbreviation they will encounter only once. Instead, write the full term each time.

This rule applies per section in some style guides (APA) and per manuscript in others. Check your target journal’s author guidelines.

Excessive abbreviation is a common problem in manuscripts by researchers who are deeply familiar with their field’s jargon. You know that ANOVA, SEM, CFI, RMSEA, and TLI are all routine terms. Your reader, who may be a generalist reviewer, does not. Use abbreviations judiciously. A manuscript with 20+ abbreviations in the first two pages is not efficient; it is a barrier to comprehension.

Abbreviations in Specific Contexts

Abstracts. Most style guides (including APA) require abbreviations to be defined again in the abstract, even if they are defined in the main text. The abstract is a self-contained document and must be understandable on its own.

Titles and headings. Avoid abbreviations in titles unless the abbreviation is more widely known than the full term (e.g., DNA, HIV). In headings, use abbreviations only if they have already been defined in the text.

Beginning of a sentence. Do not start a sentence with an abbreviation. “SEM was used to test the model” should be rewritten as “Structural equation modelling (SEM) was used to test the model” (on first use) or “The SEM model was tested” (after first use). The exception is abbreviations that are always written as such (e.g., DNA).

Tables and figures. Define abbreviations used in tables and figures in a note below the table or in the figure caption, even if they are defined in the main text. Readers often look at tables and figures without reading the surrounding text.

Theses. In a thesis, redefine abbreviations at the start of each chapter. Examiners often read chapters independently, and an abbreviation defined in Chapter 1 should not require the reader to flip back 50 pages. A glossary of abbreviations at the beginning of the thesis (after the table of contents) is also recommended.

Types of Abbreviations

Acronyms are formed from the initial letters of a multi-word term and pronounced as a word: NASA, UNESCO, ANOVA, AIDS. They are written in all capitals without periods.

Initialisms are formed from the initial letters but pronounced letter by letter: WHO, GDP, SEM, MRI. They are also written in all capitals without periods.

Contractions shorten a word by removing letters from the middle: Dr, Mr, Prof. In British English, contractions that end with the same letter as the full word do not take a period (Dr, Mr). In American English, they do (Dr., Mr.).

Latin abbreviations are common in academic writing. “e.g.” (exempli gratia, “for example”), “i.e.” (id est, “that is”), “et al.” (et alii, “and others”), “etc.” (et cetera, “and so on”), “cf.” (confer, “compare”). APA recommends using “e.g.” and “i.e.” only inside parentheses; outside parentheses, write “for example” and “that is.” Most other style guides allow them in running text.

Units of measurement follow specific conventions. SI units (kg, mL, cm, Hz) are abbreviations but are not defined on first use because they are standardised. They are written without periods and do not take a plural “s” (5 kg, not 5 kgs). For more on unit formatting conventions, see our post on spacing between numbers and unit symbols.

Common Abbreviation Mistakes

Defining an abbreviation and then never using it. If you write “the International Monetary Fund (IMF)” and then never use “IMF” again, remove the parenthetical definition. It clutters the text.

Using different abbreviations for the same term. If you define “support vector machine” as “SVM” in the methodology, do not switch to “SVMs” or “S.V.M.” later in the paper. Pick one form and use it consistently.

Pluralising abbreviations incorrectly. Add a lowercase “s” without an apostrophe: “SVMs,” “PhDs,” “URLs.” Not “SVM’s” (which implies possession, not plurality).

Creating unnecessary abbreviations. If the term is short enough to write in full without disrupting readability, do not abbreviate it. “University” does not need to be abbreviated to “Uni.” “Participants” does not need to be “Ps.”

Conclusion

Abbreviations are a tool for efficiency, not a substitute for clear writing. Define them on first use, use them only when the term appears frequently, and maintain consistency throughout the manuscript. In a thesis, redefine in each chapter and provide a glossary. When in doubt, write the term in full.

Need your manuscript checked for abbreviation consistency? PM Proofreading’s editing service checks every abbreviation for correct definition, consistent usage, and adherence to your style guide. Upload your manuscript and get a quote.

Further Reading

• Overall English Grammar Review for Non-Native Researchers
• Capitalization Rules in English: A Guide
• Space Between Number and Temperature Degree Symbol
• A Quick Guide to Punctuation for Non-Native Researchers

Frequently Asked Questions

Do I need to define abbreviations in the abstract?

Yes. Most style guides require abbreviations to be defined again in the abstract because the abstract is treated as a self-contained document. Readers who encounter your abstract in a database may not have access to the full paper. Define abbreviations on first use in the abstract, then define them again on first use in the main text.

Should I include a list of abbreviations in my thesis?

Yes. A glossary of abbreviations, placed after the table of contents, helps examiners quickly look up terms without searching through the text. Additionally, redefine abbreviations at the start of each chapter, since examiners often read chapters independently.

Can I start a sentence with an abbreviation?

Generally no. Rephrase the sentence so the abbreviation does not come first. Instead of “SEM was used,” write “Structural equation modelling (SEM) was used” or “The SEM analysis was conducted.” Exceptions exist for abbreviations that are always written as such (DNA, HIV), but these are rare.

How many abbreviations are too many in an academic paper?

There is no fixed limit, but if you are introducing more than five to seven abbreviations in a single paper, consider whether all of them are necessary. Each abbreviation adds cognitive load for the reader. Only abbreviate terms that appear three or more times and that are significantly shorter as abbreviations.