Appendixes or Appendices: Which Plural Should You Use in 2026?

I know how confusing English plurals can feel, especially when two words seem almost identical.You may have seen both “appendixes” and “appendices” and wondered which one is actually correct.The truth is that both forms are acceptable, but they are often used in different contexts.

I will help you understand the difference without complicated grammar rules.By the end, you will know exactly which word to use in your writing and conversations.Let’s clear up this common confusion so you can write with greater confidence.

Quick Answer

Both appendixes and appendices are correct plural forms of the noun appendix.

However, appendices is traditionally preferred when referring to supplementary sections in books, reports, dissertations, and academic documents. Appendixes is more commonly used when discussing multiple anatomical appendixes or in less formal contexts.

For academic and professional writing, appendices remains the most widely accepted choice.

Quick Comparison Table

How Are These Words Pronounced?

Appendix

IPA (US): /əˈpɛn.dɪks/

IPA (UK): /əˈpen.dɪks/

Appendixes

IPA: /əˈpɛn.dɪk.sɪz/

Syllables: ap-pen-dix-es

Appendices

IPA: /əˈpɛn.dɪ.siːz/

Syllables: ap-pen-di-ces

Pronunciation Difference

The difference appears only in the ending:

• Appendixes ends with “iks-iz”
• Appendices ends with “i-seez”

Both pronunciations are considered correct.

Meaning and Usage

Meaning of Appendix

An appendix generally has two major meanings:

1. A supplementary section at the end of a book, report, thesis, or document.
2. A small tube-shaped organ attached to the large intestine.

Examples

• The report includes an appendix containing survey results.
• The doctor removed his appendix during surgery.

Meaning of Appendixes

Appendixes is the regular English plural form created by adding -es to appendix.

Examples

• The biology textbook discussed diseased appendixes.
• Several appendixes were examined during the study.

While correct, it is less common in academic publishing.

Meaning of Appendices

Appendices is the traditional Latin-derived plural form of appendix.

Examples

• The dissertation contains three appendices.
• Additional charts are included in the appendices.
• Refer to Appendix A and Appendix B in the appendices section.

This form dominates academic, legal, and professional writing.

Main Difference Between Appendixes and Appendices

Grammar Rule Section

Why Are There Two Plurals?

English contains many words borrowed from Latin.

Some words keep their original Latin plurals while also developing regular English plurals.

Examples include:

Over time, both forms became acceptable in English.

Standard Rule

• Appendices = preferred in formal writing.
• Appendixes = acceptable alternative.

Origin and Etymology

The word appendix comes from the Latin word appendix, meaning:

“something attached” or “an addition.”

It derives from the Latin verb appendere, meaning:

“to hang upon” or “attach.”

Historically, scholars preserved the Latin plural appendices.

As English evolved, speakers naturally created the regular plural appendixes, following standard English pluralization rules.

This is why both forms exist today.

Dictionary Comparison

Oxford English Dictionary

Oxford recognizes both appendixes and appendices as valid plurals of appendix.

Oxford notes that appendices is especially common for written documents.

Cambridge Dictionary

Cambridge lists both forms as correct plural versions.

It commonly illustrates appendices in academic examples.

Merriam-Webster

Merriam-Webster accepts both plurals and notes differing usage preferences.

Collins Dictionary

Collins identifies both forms as standard English.

It highlights the widespread use of appendices in formal contexts.

Are Both Words Correct?

Yes.

This comparison belongs to Category B: Two Correct Words With Different Uses.

Neither word is a misspelling.

Both are recognized by major dictionaries and style guides.

However:

• Appendices is usually preferred in academic, publishing, and professional contexts.
• Appendixes remains grammatically correct and appears more often in general English and anatomical discussions.

British vs American English

Unlike color vs colour or center vs centre, this distinction is not regional.

Both British and American English accept both forms.

Comparison Table

There is no significant regional difference.

Which Form Is More Common?

Modern publishing data consistently shows that appendices is more common.

Academic Writing

• Highly preferred
• Seen in dissertations
• Common in scholarly journals

Professional Writing

• Frequently used
• Preferred in reports
• Common in manuals

Books

Publishers generally favor appendices.

Websites

Both forms appear online, but appendices still dominates educational and authoritative content.

Overall Trend

When Should You Use Each Word?

Academic Writing

Use appendices.

Examples:

• Research papers
• Theses
• Dissertations
• Scholarly articles

Example:

The appendices contain the survey questionnaires.

Professional Writing

Use appendices.

Example:

Supporting financial statements are located in the appendices.

Casual Writing

Either form is acceptable.

Example:

I added several appendixes to the document.

Journalism

Most style-conscious publications favor appendices.

Example:

Relevant documents appear in the report’s appendices.

Common Mistakes

Mistake 1: Assuming Appendixes Is Wrong

Incorrect Thinking:

Appendixes is not a real word.

Correct:

Appendixes is a recognized plural form of appendix.

Explanation: Major dictionaries accept it.

Mistake 2: Using Singular and Plural Together

Incorrect:

The appendixes contains data.

Correct:

The appendixes contain data.

Explanation: Plural nouns require plural verbs.

Mistake 3: Mixing Styles in One Document

Incorrect:

See the appendices in Chapter 5. Additional appendixes appear later.

Correct:

See the appendices in Chapter 5. Additional appendices appear later.

Explanation: Maintain consistency.

Real-Life Examples

Academic Context

The appendices include interview transcripts.

Business Context

Financial projections are listed in the appendices.

Legal Context

Refer to the appendices attached to the agreement.

Medical Context

Surgeons studied inflamed appendixes.

Educational Context

The textbook contains several appendices with practice exercises.

Synonyms

Synonyms for Appendix (Document Meaning)

• Supplement
• Attachment
• Addendum
• Annex
• Enclosure
• Supporting material
• Reference section

Synonyms for Appendices

• Supplements
• Addenda
• Annexes
• Attachments
• Supporting documents

Synonyms for Appendixes

• Supplemental sections
• Additional materials
• Attachments

Antonyms

Since appendix refers to an addition, possible opposites include:

For Appendix

• Main text
• Core content
• Primary section
• Body

For Appendices

• Main chapters
• Principal content
• Central material

Memory Trick

A simple way to remember:

Think Academic = Latin

Appendices sounds more scholarly and Latin-based.

Use it for:

• Research papers
• Reports
• Books
• Formal documents

Think Everyday = English

Appendixes follows the regular English plural rule.

Use it when formality is not important.

Memory formula:

Formal writing → Appendices
Everyday English → Appendixes

Similar Confusing Words

Many English words have both regular and Latin plurals.

Indexes vs Indices

• Indexes = general use
• Indices = mathematics and finance

Matrixes vs Matrices

• Matrixes = general use
• Matrices = mathematics

Vertexes vs Vertices

• Vertexes = acceptable
• Vertices = more technical

Cactuses vs Cacti

• Both correct
• Cacti often preferred

Why Do People Search “Appendixes or Appendices”?

Most users search this phrase because they want to know:

• Which form is correct
• Whether one is a mistake
• Which version professors prefer
• What dictionaries recommend
• Which plural should appear in reports
• Whether both forms are acceptable

Common Search Queries

• Is appendixes correct?
• What is the plural of appendix?
• Appendices vs appendixes meaning
• Which is grammatically correct?
• How do you pluralize appendix?
• Is appendices singular or plural?
• Can I use appendixes in academic writing?
• What do style guides recommend?

FAQs

1. Which word is correct: appendixes or appendices?

Both are correct plural forms of appendix.

2. Are both words recognized by dictionaries?

Yes. Oxford, Cambridge, Merriam-Webster, and Collins accept both.

3. Which form is preferred in academic writing?

Appendices is generally preferred.

4. Is appendixes a misspelling?

No. It is a legitimate English plural.

5. What is the plural of appendix?

The plural can be either appendixes or appendices.

6. Which form sounds more formal?

Appendices.

7. Do universities prefer appendices?

Most universities and academic publishers do.

8. Is there a British vs American difference?

No significant difference exists.

9. Can I use appendixes in professional documents?

Yes, but appendices is usually preferred.

10. Which form appears more often in books?

Appendices appears more frequently.

11. Is appendices singular?

No. Appendices is plural.

12. Why does appendix have two plurals?

Because it combines Latin linguistic heritage with modern English pluralization patterns.

Expert Recommendation

Editors, teachers, publishers, and major style guides generally recommend appendices when referring to supplementary sections in documents.

Dictionaries recognize both forms, so neither is wrong. However, if you want the safest choice for academic, professional, or published writing, appendices is usually the best option.

Use appendixes when discussing anatomical appendixes or when a less formal style is acceptable.

Final Verdict

The debate over appendixes or appendices is not about right versus wrong.

Both forms are grammatically correct and dictionary-approved.

The real difference lies in convention and context.

Key Takeaways

• Both appendixes and appendices are correct.
• Appendices is the traditional Latin plural.
• Appendixes is the regular English plural.
• Academic and professional writing usually prefers appendices.
• Medical and informal contexts may use either form.
• There is no major British vs American English distinction.
• Consistency within a document is more important than the choice itself.

Practical Usage Advice

If you’re writing a thesis, dissertation, report, book, or professional document, choose appendices.

If you’re writing informally or discussing anatomical organs, appendixes is also perfectly acceptable.

In 2026, both forms remain correct—but appendices continues to be the preferred choice for formal writing.

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