Appendices Or Appendixes: What is the Difference & Which is Correct?

“Appendices” and “appendixes” are both accepted plural forms of the word “appendix,” which often confuses English learners and writers. While both are correct, they are used in slightly different contexts and styles. Understanding when to use each one helps improve your grammar, writing clarity, and confidence.

Comparison Overview

The words appendices and appendixes are both plural forms of appendix. They refer to additional sections added at the end of a book, report, or document to provide extra information. The main difference lies in usage style and context.

Appendices is more common in formal, academic, and professional writing.

Appendixes is often used in general English and can also refer to the anatomical organ in medical contexts.

Both are grammatically correct, but choosing the right one depends on your audience and purpose.

Definition of Appendices

Appendices is the traditional Latin plural form of appendix.

It is mainly used in:

• Academic papers
• Research reports
• Books
• Formal documents
• Professional writing

Its purpose is to add supporting material such as charts, tables, references, or detailed explanations without interrupting the main text.

Example:
“The research paper includes three appendices at the end.”

Definition of Appendixes

Appendixes is the regular English plural form of appendix.

It is commonly used in:

• Everyday English
• Informal writing
• General documents
• Medical contexts

It follows standard English plural rules, making it easier for many learners.

Example:
“The textbook contains two appendixes with extra exercises.”

Main Differences Between Appendices and Appendixes

Feature	Appendices	Appendixes
Plural type	Latin plural	English plural
Formality	More formal	Less formal
Common in academic writing	Yes	Less common
Common in casual writing	Less common	Yes
Used in medicine	Sometimes	Common
Preferred in style guides	Often preferred	Accepted

Origin and Historical Usage

The word appendix comes from Latin, where many nouns form plurals differently than in English.

That is why appendices developed as the classical plural.

Over time, English adopted appendixes as a simpler modern alternative, which is why both forms now exist.

Which Form Is More Common Today?

In modern writing:

• Universities and publishers often prefer appendices.
• Everyday writers may choose appendixes.
• Medical writing often uses appendixes when referring to the body organ.

So context matters more than strict correctness.

Grammar Guide

Both words are plural nouns, but their usage depends on style and context.

How each term is used in sentences

Appendices

• The thesis includes several appendices.
• Please review the appendices for supporting data.

Appendixes

• The manual has two appendixes.
• Doctors studied the removed appendixes.

Common mistakes learners make

Mistake 1: Thinking only one is correct.
Correction: Both are correct.

Mistake 2: Using appendixes in highly formal academic writing where appendices is expected.

Mistake 3: Mixing both forms in the same document.

Simple rules to remember

• Writing a research paper? Use appendices.
• Writing casually? Appendixes is fine.
• Talking about body organs? Usually use appendixes.

Quick tips for writing and speaking

• Stay consistent throughout your document.
• Match your audience and tone.
• Check your style guide if writing professionally.

When to Use Each One

Use appendices when:

• Writing essays
• Publishing books
• Creating academic reports
• Preparing business documents
• Following formal style guides

Use appendixes when:

• Writing informally
• Teaching beginners
• Referring to anatomy
• Using plain English style

When NOT to Use Each One

Do not use appendices when:

• Writing for very young learners who may find it confusing
• Your style guide specifically prefers appendixes

Do not use appendixes when:

• Writing formal academic papers unless permitted
• Your institution prefers classical plurals

Which One to Use (Decision Guide)

Ask yourself these questions:

Is the writing formal or academic?
Use appendices.

Is the writing casual or general?
Use appendixes.

Is it about the human body?
Usually use appendixes.

Need a safe universal choice for academic work?
Choose appendices.

Real-World Practical Examples

Appendices Examples

1. The dissertation includes five appendices with survey data.
2. Please review the appendices before submitting the report.
3. The legal document contains supporting evidence in the appendices.
4. The textbook lists formulas in its appendices.
5. Scientists attached detailed charts in the appendices.

Appendixes Examples

1. The workbook has two appendixes for extra practice.
2. Several appendixes were examined during the medical study.
3. The guidebook includes helpful appendixes for travelers.
4. Students used the appendixes to review grammar rules.
5. The software manual contains technical appendixes.

Self-Assessment (Fill in the Blanks)

1. My thesis includes three ______ for extra charts.
2. The doctor studied several removed ______.
3. Academic books often use ______.
4. Casual manuals may use ______.
5. The report’s supporting tables are in the ______.
6. Medical journals sometimes mention inflamed ______.
7. Formal writing usually prefers ______.
8. Everyday English often accepts ______.
9. The professor asked us to check the ______.
10. The biology text discussed human ______.
11. This research article has detailed ______.
12. The user guide includes two ______.
13. Universities usually choose ______.
14. Plain English may choose ______.
15. The book’s references appear in the ______.
16. Surgeons removed two infected ______.
17. My academic editor suggested ______.
18. The simple handbook uses ______.
19. Formal reports commonly contain ______.
20. Medical records described damaged ______.

Answers

1. appendices
2. appendixes
3. appendices
4. appendixes
5. appendices
6. appendixes
7. appendices
8. appendixes
9. appendices
10. appendixes
11. appendices
12. appendixes
13. appendices
14. appendixes
15. appendices
16. appendixes
17. appendices
18. appendixes
19. appendices
20. appendixes

Final Verdict

Both appendices and appendixes are correct plural forms of appendix, but they serve different writing styles. Appendices is the preferred choice in formal, academic, and professional writing because it sounds more traditional and polished. Appendixes is perfectly acceptable in everyday English and is often preferred in medical contexts. If you are unsure, choose appendices for formal writing and appendixes for casual or anatomical use.

Conclusion About Appendices Or Appendixes

Both appendices and appendixes are correct plural forms of appendix, with differences based mainly on style and context rather than strict grammar rules. Appendices is preferred in academic, formal, and professional writing because it follows traditional Latin usage and sounds more polished. Appendixes is commonly used in general English and often appears in everyday writing and medical references. This distinction helps writers maintain clarity and consistency. In research papers, reports, and scholarly documents, appendices is usually the safest choice. In casual or informal communication, appendixes is also acceptable. Both forms are correct, so choose one and use it consistently throughout your writing for clarity and professionalism.

FAQs

What is the difference between appendices and appendixes?

Both appendices and appendixes are plural forms of appendix, but the difference is mainly stylistic. Appendices is the traditional Latin form used in academic and formal writing, while appendixes is the modern English form used in general and medical contexts. Both are correct, and the choice depends on tone, audience, and writing style rather than grammar correctness.

When should appendices be used?

Appendices is typically used in academic papers, research reports, books, and professional documents. It is preferred when a formal tone is required and when following style guides that favor classical language forms. Writers use appendices to present supporting materials such as tables, references, or extra data without interrupting the main content of the document.

When should appendixes be used?

Appendixes is used in general English writing, informal content, and medical contexts. It is especially common when referring to the anatomical organ. Writers choose appendixes when they want a simpler, more modern plural form. It is acceptable in most situations, especially when formal academic tone is not required.

Are both appendices and appendixes correct?

Yes, both appendices and appendixes are grammatically correct plural forms of appendix. Neither is wrong. The difference lies in preference, style guides, and context. Academic writing often prefers appendices, while everyday usage and medical contexts may use appendixes. Choosing between them depends on consistency and audience expectations.

Which form is more formal?

Appendices is considered more formal because it comes from Latin pluralization rules and is widely used in academic, legal, and professional writing. It gives a more traditional and scholarly tone. Appendixes is less formal and is generally used in everyday language or specific medical references.

Is appendixes used in medicine?

Yes, appendixes is commonly used in medical contexts, especially when referring to the human appendix organ. Doctors, textbooks, and medical reports may use this form to describe multiple anatomical structures or cases. However, both forms can still appear depending on style preferences in medical literature.

Can appendices and appendixes be used interchangeably?

Yes, in many contexts they can be used interchangeably because both are correct plural forms. However, consistency is important. Mixing both forms in one document can look unprofessional. It is better to choose one form based on tone and stick with it throughout the entire text.

Why do both forms exist?

Both forms exist because English borrowed the word appendix from Latin. The Latin plural is appendices, while English also developed a regular plural form appendixes. Over time, both became accepted in modern usage, with different preferences emerging in academic, general, and medical writing contexts.

Which is better for academic writing?

Appendices is generally better for academic writing because it aligns with traditional scholarly style and is preferred by many academic style guides. It is commonly used in theses, dissertations, and research papers. It helps maintain a formal tone and is widely recognized in educational institutions.

What are common mistakes with appendices and appendixes?

Common mistakes include assuming one form is incorrect, mixing both forms in the same document, or using appendixes in highly formal academic work where appendices is expected. Another mistake is not following the required style guide. Consistency and understanding the context help avoid these errors.