Appendices Or Appendixes? Clarifying Usage

“Appendices or Appendixes? Clarifying Usage” refers to understanding the correct plural form of the word appendix, which can either denote supplementary material at the end of a document or a small anatomical organ. In English, both appendices and appendixes are accepted plural forms, but their usage depends on the context—literary or scientific. This topic addresses a common grammatical dilemma, especially for students, writers, researchers, and professionals who aim to use language accurately and clearly.

Language often evolves in unpredictable ways, and this small detail in word choice reveals the fascinating tug-of-war between traditional Latin roots and modern English conventions. What may seem like a trivial choice between appendices and appendixes actually reflects broader trends in linguistic adaptation, academic precision, and even anatomical terminology. Understanding the difference can elevate your communication, whether you’re drafting a scholarly paper or describing a medical condition.

By exploring Appendices or Appendixes? Clarifying Usage, you gain clarity on when each form is appropriate. From dissecting historical origins to offering practical usage examples, this guide demystifies a point of confusion that appears more often than you’d expect. Whether you’re editing a report or learning about anatomy, Appendices or Appendixes? Clarifying Usage provides the insight you need to use both terms with confidence.

What Does “Appendix” Mean?

The word “appendix” can refer to two main things:

1. In writing, it’s a section added at the end of a book or document. It includes supplementary materials like charts, data, and references that support the main text.
2. In medicine, it’s a small tube-shaped organ attached to the large intestine. This human appendix is part of the digestive system and can become inflamed, leading to appendicitis.

So depending on what you’re writing about—a book or the human body—you’ll need to choose the right plural.

Singular and Plural Forms of Appendix

The singular form is always “appendix.”

But the plural form can be either:

• Appendices – This is the Latin plural and is commonly used in academic writing, books, and research papers.
• Appendixes – This is the anglicized form and is often used in medical contexts and casual English.

Both are correct, but which one you choose depends on your audience and purpose.

Origins of the Word Appendix

The word “appendix” comes from Latin. It originates from the Latin word “appendere,” meaning “to hang upon.” In classical Latin, the plural of appendix is “appendices.”

As English evolved, it adopted both Latin and more simplified, phonetic spellings. This is why we now have two plural options: the classical “appendices” and the modern English “appendixes.”

This duality often causes confusion, especially among students and professionals who want to write properly but aren’t sure which to use.

Appendices vs Appendixes – When to Use Each One

Here’s the rule of thumb:

Use “appendices” when writing about:

• Books and publications
• Academic theses and reports
• Government documents
• Scientific research
• Technical manuals

Example: “The final report includes several appendices for supporting data.”

Use “appendixes” when writing about:

• Anatomy and physiology
• Medical case studies
• Surgery or diagnosis
• Health and biology textbooks
• General, informal language

Example: “The patient had two inflamed appendixes, which is an unusual medical case.”

This chart summarizes the distinction:

Field	Preferred Plural
Academic writing	Appendices
Scientific papers	Appendices
Book publishing	Appendices
Medical documentation	Appendixes
Informal language	Either is fine

What Do Style Guides Recommend?

Different style guides have different preferences for which plural form to use.

• APA Style (used in psychology, social sciences): prefers appendices
• MLA Style (used in humanities): prefers appendices
• Chicago Manual of Style: recommends appendices in formal documents
• AMA Manual of Style (used in medical writing): recommends appendixes
• Associated Press (AP) Style: allows appendixes, especially in journalism

These choices reflect the broader rule: use appendices in formal academic or professional writing, and appendixes in medical or casual contexts.

Examples of Usage in Sentences

Here are real-life examples to help clarify usage:

Academic example:
“The report contains three appendices: raw data, interview transcripts, and additional charts.”

Medical example:
“Doctors found that the patient had duplicate appendixes, a rare anatomical variation.”

Everyday example:
“I added two appendices to my user guide so readers could see the full test results.”

Examples in Context

Using “Appendix” (singular):

• The report includes an appendix with detailed survey results.
• I found a helpful chart in the appendix of the user manual.
• Please check the appendix for the full list of references.
• The appendix contains extra information that supports the main text.
• He had to undergo surgery to remove his inflamed appendix.
• The appendix at the end of the book provides definitions of key terms.
• In biology class, we studied the role of the human appendix.
• My thesis has one appendix that includes raw data and calculations.

“Appendices” (plural in reference to a book or document):

• The appendices at the end of the textbook include extra exercises.
• I added several appendices to my report to show supporting data.
• The research paper includes appendices with charts and graphs.
• All the financial tables are placed in the appendices of the annual report.
• The appendices in this manual list all the technical specifications.
• Students should review the appendices for additional reading materials.
• The thesis contains three appendices with interview transcripts.
• You’ll find detailed case studies in the appendices of the proposal.

“Appendices” (plural in reference to anatomy):

• The surgeon found two inflamed appendices during the operation.
• Some rare medical cases involve patients born with multiple appendices.
• The study compared the sizes of appendices in different mammals.
• Scientists are researching the possible functions of vestigial appendices.
• The doctor explained how appendices can vary in length and position.
• In rare conditions, duplicated appendices may cause diagnostic confusion.
• Veterinarians sometimes discover infected appendices in animals.
• The anatomy textbook shows diagrams of different types of appendices.

Common Mistakes and How to Avoid Them

1. Using the wrong plural in the wrong context
   • Wrong: “The doctor removed the appendices during surgery.”
   • Right: “The doctor removed the appendixes during surgery.”
2. Mixing plural forms in one document
   • Avoid switching between appendices and appendixes. Be consistent.
3. Thinking one form is incorrect
   • Both are correct; it’s the usage that determines which one to pick.

Quick Rule of Thumb

Not sure which one to use? Here’s a simple guide:

• If it’s about books, papers, or documents: use appendices
• If it’s about anatomy or medicine: use appendixes
• For casual writing or conversation: both are acceptable, but appendices sounds more formal

Formatting Appendices in Academic Writing

When including appendices in academic or professional documents, follow these guidelines:

• Each appendix starts on a new page
• Label them Appendix A, Appendix B, and so on
• Include a clear title for each appendix
• Refer to each appendix in the body of your text (e.g., “see Appendix C”)

Example format:

Appendix A: Questionnaire Used in the Survey
Appendix B: Interview Transcript
Appendix C: Raw Data Tables

This kind of structure is often required in theses, research papers, and business reports.

Can Humans Have Multiple Appendixes?

Yes, although it’s rare. Some people are born with more than one appendix, a condition known as appendiceal duplication. According to medical literature, this condition affects less than 0.005% of the population.

In these rare cases, the correct plural form is clearly appendixes, because it refers to anatomical structures.

Case Study: Appendices in a Research Paper

A university student working on a thesis titled Impact of Soil pH on Plant Growth included several appendices:

• Appendix A: Field Data Tables
• Appendix B: Photos of Experimental Setup
• Appendix C: Interview with Local Farmers

These appendices added depth and credibility to the paper without interrupting the main narrative. This is a perfect example of the use of appendices in academic writing.

Conclusion

In summary, Appendices or Appendixes? Clarifying Usage helps us understand the correct way to use these words. Both are right, but they are used in different situations. Use appendices when talking about extra sections in books or reports. Use appendixes when talking about the organ in the human body. Knowing when to use each one makes your writing more clear and correct.

Understanding the topic Appendices or Appendixes? Clarifying Usage is useful for students, writers, and anyone working with words. It shows how English can have more than one right answer, depending on context. With this knowledge, you can make better choices and write with confidence. Appendices or Appendixes? Clarifying Usage is a simple example of how small details in language can make a big difference.

FAQs

1. What’s the correct plural of “appendix” in academic writing in 2025?
Appendices is the preferred and widely accepted plural in academic and professional documents.

2. Is “appendixes” still used in modern English?
Yes, appendixes is still correct, mainly used in medical or anatomical contexts.

3. Do major style guides prefer “appendices” or “appendixes”?
Most current style guides like APA 7th, MLA 9th, and Chicago 17th edition recommend using appendices for documents.

4. Can you use both forms in the same document?
No, it’s best to choose one form based on context and stay consistent throughout the text.

5. Are both “appendices” and “appendixes” listed in modern dictionaries like Oxford or Merriam-Webster (2025 editions)?
Yes, both are listed as valid plural forms of “appendix,” with usage notes based on subject matter.