The Appendices or Appendixes guide helps writers understand the correct plural of appendix while avoiding confusion in formal writing today. Have you ever finished writing a report, thesis, business document, or essay and wondered which form is right? You are not alone because many English speakers, students, and professionals become confused when both appendices and appendixes are accepted forms found in dictionaries, academic papers, and published books. This common confusion can create uncertainty, inconsistent writing, and unnecessary edits.
The difference between these two spellings comes from their origin and usage. The word appendix comes from Latin, allowing its plural to be formed in different ways. Both versions are used in real-world contexts, but style recommendations may change by field. This guide explains the meanings, grammar rules, and applications in a clear and simple way.
In formal documentation, publishing, legal, and technical work, the noun refers to supplementary material included at the end of a document, and choosing the right form helps avoid real mistakes that may make your work appear careless, wrong, or outdated.
What Does “Appendix” Mean?
Before discussing the plural forms, it’s helpful to understand the singular word.
An appendix is supplementary material added to the end of a document, book, report, thesis, or research paper. It contains information that supports the main content without interrupting the flow of the text.
For example, an appendix might include:
- Data tables
- Survey results
- Interview transcripts
- Charts and graphs
- Technical specifications
- Reference documents
- Additional research findings
In anatomy, the word refers to the small pouch attached to the large intestine, commonly called the vermiform appendix.
Definition of Appendix
| Context | Meaning |
| Academic Writing | Supplemental information attached to a document |
| Business Reports | Supporting materials and evidence |
| Technical Documents | Additional data or references |
| Medicine | A small organ connected to the large intestine |
Because the word appears in both formal writing and medical contexts, its plural forms have developed slightly different usage patterns.
Appendices vs. Appendixes: The Short Answer
If you’re looking for the quickest answer possible, here it is:
Both appendices and appendixes are grammatically correct plural forms of appendix.
The preferred choice depends on the context.
Quick Comparison
| Singular | Plural | Most Common Usage |
| Appendix | Appendices | Academic and formal writing |
| Appendix | Appendixes | General English and anatomy |
In many universities, you’ll see appendices used almost exclusively. In medical discussions about multiple anatomical appendixes, you’ll often encounter appendixes.
That distinction isn’t absolute, but it reflects modern usage patterns.
Read more: Inclosed vs Enclosed: Which Spelling Is Correct?
Why Are There Two Plural Forms?
The answer goes back thousands of years.
English borrows heavily from Latin. Many words entered English while retaining their original Latin plural forms.
The word appendix comes from the Latin word appendix, meaning “something attached.”
In Latin, words ending in -ix often form their plurals by changing to -ices.
Examples include:
| Singular | Latin Plural |
| Appendix | Appendices |
| Index | Indices |
| Matrix | Matrices |
| Vertex | Vertices |
Over time, English speakers simplified many of these plurals.
As a result, alternative English-style plurals emerged:
| Traditional Plural | English Plural |
| Indices | Indexes |
| Matrices | Matrixes |
| Appendices | Appendixes |
Both systems survived, which explains why two accepted plurals exist today.
When to Use “Appendices”
If you’re writing in a formal environment, appendices is usually the safest choice.
Many academic institutions, professional publishers, and research journals strongly favor this version.
Common Places Where “Appendices” Appears
- Research papers
- Master’s theses
- Doctoral dissertations
- Scientific journals
- Government publications
- Policy reports
- Technical documentation
- White papers
Example Sentences
- The survey responses are included in the appendices.
- Detailed calculations appear in the appendices at the end of the report.
- Readers can review supporting evidence in the appendices.
Why Formal Writers Prefer Appendices
Several factors contribute to its popularity:
- Preserves the traditional Latin form.
- Appears more scholarly.
- Matches academic style conventions.
- Aligns with expectations in higher education.
For instance, a doctoral dissertation containing ten supporting sections would almost always refer to them as appendices rather than appendixes.
When to Use “Appendixes”
Although some people assume appendixes is incorrect, dictionaries recognize it as a valid plural.
In certain situations, it may even be preferred.
Common Uses of Appendixes
- Everyday writing
- General publications
- Informal communication
- Medical discussions
- Educational materials aimed at general audiences
Example Sentences
- The biology textbook included diagrams of healthy and inflamed appendixes.
- Several patient case studies examined damaged appendixes.
- The writer added two appendixes to provide additional examples.
Why Some Writers Prefer Appendixes
Many writers choose it because:
- It follows standard English plural rules.
- It feels more intuitive.
- It is easier for some readers to recognize.
- It avoids unfamiliar Latin forms.
Think of it this way: while “children” is an irregular plural that English speakers learn naturally, many readers are less familiar with words like appendices and matrices.
Appendices vs. Appendixes in Academic Style Guides
APA Style
The American Psychological Association generally uses appendices.
Research papers, dissertations, and scientific manuscripts following APA standards almost always adopt this form.
Example: See Appendices A–D for complete survey data.
MLA Style
The Modern Language Association also favors appendices when referring to supplemental sections in scholarly work.
Chicago Manual of Style
Chicago style follows similar conventions.
Publishers using Chicago typically prefer appendices in books, reports, and manuscripts.
Academic Consensus
| Writing Context | Preferred Form |
| Research Papers | Appendices |
| Theses | Appendices |
| Dissertations | Appendices |
| Academic Journals | Appendices |
| Technical Reports | Appendices |
If you’re submitting work for school or publication, choose appendices unless instructed otherwise.
Appendices vs. Appendixes in Medical Usage
Medicine introduces an interesting twist.
Unlike academic writing, healthcare professionals often refer to anatomical organs rather than document sections.
The Human Appendix
The appendix is a narrow tube attached to the large intestine.
Although researchers once considered it useless, modern studies suggest it may support gut bacteria and immune function.
Medical Example
A surgeon discussing multiple patients might write:
- Several inflamed appendixes required emergency removal.
Sample Medical Contexts
| Sentence | Common Choice |
| The report examined diseased appendixes. | Appendixes |
| Surgical records identified ruptured appendixes. | Appendixes |
| Supporting medical charts appear in the appendices. | Appendices |
Notice how the context changes the preferred form.
Which Form Is More Common Today?
Modern English shows a clear pattern:
- Appendices dominates formal writing.
- Appendixes appears more often in general usage.
- Academic publications overwhelmingly favor appendices.
- Medical discussions may use either form.
Why Appendices Remains Strong
- University standards
- Academic publishing traditions
- Scientific writing conventions
- Professional expectations
Why Appendixes Continues to Survive
At the same time, English naturally moves toward simpler grammar.
As a result, many writers prefer forms that follow familiar plural rules.
Common Mistakes Writers Make
Assuming Appendixes Is Wrong
One of the biggest mistakes is believing only appendices is acceptable.
Major dictionaries recognize both forms.
Mixing Both Forms
Avoid switching between forms within the same document.
Incorrect Example
- Appendix A appears below.
- Additional appendices follow.
- The remaining appendixes contain data.
Correct Example
Choose one style and stick with it throughout your document.
Ignoring Audience Expectations
A university professor may expect appendices.
A general audience may feel more comfortable reading appendixes.
Always consider who will read your work.
How to Choose the Right Form Every Time
Ask yourself a few simple questions.
Is the Document Academic?
If yes, choose appendices.
Is the Document Professional?
If yes, choose appendices.
Is the Topic Medical Anatomy?
If yes, appendixes often works well.
Are You Writing for a General Audience?
Either form may work, though appendixes sometimes feels more natural.
Quick Decision Guide
| Situation | Recommended Form |
| Research Paper | Appendices |
| Thesis | Appendices |
| Dissertation | Appendices |
| Government Report | Appendices |
| Technical Manual | Appendices |
| Medical Discussion | Appendixes |
| Educational Article | Either |
| Blog Post | Either |
Appendices vs. Appendixes Examples in Real Sentences
Academic Examples
- The statistical models appear in the appendices.
- Readers can find survey results in the appendices.
- Additional references are included in the appendices.
Business Examples
- Financial projections appear in the appendices.
- Supporting contracts are attached in the appendices.
Medical Examples
- Surgeons removed three infected appendixes during the study period.
- Researchers analyzed damaged appendixes from several patients.
General Examples
- The author added two appendixes containing maps and photographs.
- Several appendixes provide historical context.
Frequently Asked Questions
1. Are appendices and appendixes both correct words?
Yes, both appendices and appendixes are correct plural forms of appendix. The choice depends on the writing style, audience, and context. Appendices is more common in academic, formal, and traditional writing because it follows the original Latin plural form. Appendixes is also accepted and is often used in general English, especially in American writing.
2. What is the difference between appendices and appendixes?
The main difference is their origin and usage preference. Appendices comes from Latin and is often preferred in scholarly, academic, and professional documents. Appendixes follows the regular English plural pattern by adding “-es.” Although both have the same meaning, writers may choose one form based on their style guide or audience.
3. Should I use appendices or appendixes in academic writing?
In most academic writing, appendices is usually the preferred choice. Universities, research papers, and formal publications often follow traditional grammar rules and style guides that recommend Latin-based plurals. However, always check your institution’s guidelines because some organizations may accept or prefer appendixes.
4. Is appendix a singular or plural word?
Appendix is a singular noun, meaning one additional section of information added to the end of a document, book, or report. When referring to more than one additional section, you can use either appendices or appendixes as the plural form.
5. When should I use appendices instead of appendixes?
Use appendices when writing formal documents such as research papers, academic essays, legal documents, or professional reports. It gives your writing a more traditional and scholarly tone. Use appendixes when following modern English preferences or when your audience is more familiar with regular English plural forms.
6. Can using the wrong plural form of appendix affect my writing?
Using either form usually will not make your writing incorrect because both are recognized. However, choosing the preferred form for your specific context can make your work appear more polished, accurate, and consistent. Following a style guide helps maintain professionalism in academic, technical, and business documents.
Conclusion
Understanding the difference between appendices or appendixes helps you write with more confidence and accuracy. Both forms are correct, but the best choice depends on your audience, writing style, and context. For academic papers, professional reports, and formal documentation, appendices is often the preferred option because of its traditional Latin origin. On the other hand, appendixes is still acceptable and works well in many modern English writing situations.
The key is to stay consistent throughout your document. Whether you are preparing a thesis, business report, technical document, or published work, using the right plural form shows attention to detail and professionalism. Once you understand the usage rules, grammar differences, and real-world applications of these words, you can confidently choose between appendices and appendixes without confusion.
