Appendixes vs Appendices: Which Plural Should You Use?

Both appendixes and appendices are correct plural forms of appendix. However, writers often choose between them based on context.

Appendices is the more traditional and common choice for supplementary sections at the end of books, reports, academic papers, and legal documents. In contrast, appendixes follows the regular English plural pattern and appears in both document-related and anatomical writing.

For example:

• The report includes three detailed appendices.
• Doctors examined the patients’ appendixes.

The distinction is a usage preference rather than a strict grammar rule. Major American dictionaries accept both plurals, although some editorial styles prefer appendices for documents. Merriam-Webster, Cambridge Dictionary

Quick Answer

Both words are correct.

Use appendices for sections containing supplementary information at the end of books, reports, contracts, and research papers. It is especially common in academic and professional writing.

Use appendixes when discussing more than one anatomical appendix. You may also use it for document sections, although appendices usually sounds more traditional in that context.

• The thesis contains five appendices.
• The surgeon compared images of several appendixes.

If you need one dependable choice for a formal document, use appendices.

What Is the Plural Form of “Appendix”?

Both appendixes and appendices are correct plurals of appendix. Appendices is more common in academic, medical, and formal writing, while appendixes is often used in general English and publishing. Choose the form that matches your audience or style guide.

What Are Examples of Appendices?

In books, reports, and research papers, appendices contain extra information that supports the main text. Examples include data tables, charts, questionnaires, interview transcripts, maps, or detailed calculations that are helpful but not essential to the main discussion.

Do I Title It Appendix or Appendices?

Use Appendix when there is only one supplementary section. Use Appendices when your document contains two or more. Label each one clearly, such as Appendix A, Appendix B, and so on.

Is It Appendix or Appendices in APA?

In APA Style, use Appendix for a single appendix and Appendices when there is more than one. Each appendix should begin on a new page and be labeled with a capital letter, such as Appendix A or Appendix B.

When Should You Use Annex vs. Appendix?

An appendix contains supporting information that is closely related to the main document. An annex usually contains supplementary material that can stand on its own, such as legal documents, technical specifications, or reference materials. The choice depends on the document type and style guide.

Can an Annex Have an Appendix?

Yes. A large document can include both annexes and appendices if needed. An appendix supports the main text, while an annex provides additional standalone material. Whether both are used depends on the document’s structure and the required style guide.

Why People Confuse Them

The confusion exists because appendix has two accepted plural patterns.

The regular English pattern adds -es:

• Appendix → appendixes

The Latin-based pattern changes -ix to -ices:

• Appendix → appendices

English borrowed appendix from Latin. Consequently, it retained the Latin-style plural appendices. However, English speakers also created the regular plural appendixes.

Both forms eventually became standard. That is why dictionaries list both rather than identifying one as a misspelling.

The word’s two main meanings create another question. An appendix can be:

1. A supplementary section at the end of a document.
2. A small organ attached to the large intestine.

Writers sometimes use one plural for documents and the other for anatomy. This distinction can be useful, but it is not absolute.

Key Differences At A Glance

Context	Best Choice	Why
Academic paper	Appendices	Traditional in scholarly writing
Business report	Appendices	Common in formal documents
Legal document	Appendices	Often preferred for supplementary sections
Book	Appendices	Widely used for added reference material
Multiple anatomical organs	Appendixes	Clear and natural in medical contexts
General informal writing	Either	Both are grammatically correct
Required house style	Follow that style	Editorial consistency matters most

A simple memory rule can help:

• Documents usually have appendices.
• Bodies can have appendixes.

Still, treat this as a preference, not an unbreakable rule.

Meaning And Usage Difference

What Does Appendices Mean?

Appendices is a plural form of appendix. It most often refers to supplementary sections placed after the main text of a document.

These sections may contain:

• Charts
• Tables
• Survey questions
• Research data
• Detailed calculations
• Supporting documents
• Technical explanations
• Interview transcripts
• Reference lists

Examples:

• The appendices contain the complete survey results.
• Readers can find the technical specifications in the appendices.
• The contract includes two appendices.
• Three appendices follow the final chapter.

In longer documents, writers often label each section separately:

• Appendix A: Survey Questions
• Appendix B: Participant Data
• Appendix C: Statistical Results

Together, these sections are the document’s appendices.

What Does Appendixes Mean?

Appendixes is also a correct plural of appendix. It uses the ordinary English method of adding -es to a word ending in x.

The form can refer to supplementary document sections:

• The manual contains several appendixes.
• We moved the charts into separate appendixes.

However, appendixes is particularly useful when referring to anatomical structures:

• The surgeons examined the removed appendixes.
• The medical study compared healthy and inflamed appendixes.
• The specimens included appendixes from several patients.

Cambridge specifically presents appendixes for the anatomical meaning while accepting both forms for a book section. Meanwhile, Merriam-Webster accepts both plurals for the word generally. Cambridge Dictionary, Merriam-Webster

Do The Words Have Different Definitions?

Usually, no. Both words mean “more than one appendix.”

The main difference involves convention:

• Appendices preserves the Latin plural.
• Appendixes follows the regular English plural pattern.

Context may influence the preferred form, but it does not create two completely separate definitions.

Tone, Context, And Formality

Appendices often sounds formal, academic, or technical. Therefore, it appears frequently in theses, research papers, policy documents, and professional reports.

• Supporting evidence appears in the appendices.
• Consult Appendices A through D for complete results.

Appendixes sounds slightly more regular because it follows the familiar English plural pattern. It can appear naturally in general writing and medical discussions.

• The textbook contains several useful appendixes.
• Researchers analyzed the appendixes after surgery.

Neither form is inherently informal. In addition, neither is limited to American or British English. Both occur in standard English, although particular publishers and organizations may establish their own preferences.

For example, Microsoft’s editorial guidance requires appendices rather than appendixes. That instruction represents a house-style decision, not a universal grammar rule. Microsoft Writing Style Guide

Which One Should You Use?

Choose the form that best fits your context and required style.

Use Appendices For Supplementary Sections

Appendices is usually the safest choice when discussing added sections in:

• Books
• Research papers
• Dissertations
• Business reports
• Policy documents
• Contracts
• Instruction manuals
• Government publications

Examples:

• The report’s appendices provide regional sales figures.
• We placed the raw data in three appendices.
• Consult the appendices for additional examples.

Use Appendixes For Anatomical References

Appendixes clearly fits sentences involving multiple anatomical organs:

• The laboratory received four appendixes for examination.
• The surgeon studied differences among the appendixes.
• All the removed appendixes showed signs of inflammation.

Although appendices can also be understood anatomically, appendixes may prevent readers from initially thinking about documents.

Follow The Required Style Guide

Your school, employer, publisher, or client may require one form. If so, follow that preference throughout the document.

Consistency matters more than switching forms unnecessarily:

Inconsistent:

The first two appendices contain charts, while the remaining appendixes contain interview transcripts.

Consistent:

The first two appendices contain charts, while the remaining appendices contain interview transcripts.

If all the words refer to the same type of material, choose one plural and keep it.

When One Choice Sounds Wrong

Neither plural is grammatically wrong. Nevertheless, one may sound less natural in a particular setting.

In an academic paper, this sentence is correct but may sound less conventional:

The appendixes contain the study’s raw data.

Many academic readers would expect:

The appendices contain the study’s raw data.

In an anatomical discussion, this sentence is also possible:

The doctors examined the appendices.

However, readers may briefly wonder whether appendices refers to document sections. The following version is clearer:

The doctors examined the appendixes.

Context usually removes any uncertainty. Still, choosing the conventional form makes the sentence easier to understand immediately.

Common Mistakes And Quick Fixes

Mistake: Treating Appendixes As Incorrect

Incorrect claim:

Appendixes is not a real word.

Correct explanation:

Appendixes is an accepted plural of appendix.

Most major dictionaries recognize both plural forms.

Mistake: Writing Appendix’s As A Plural

Incorrect:

The book has three appendix’s.

Correct:

The book has three appendices.

Also correct:

The book has three appendixes.

An apostrophe does not create an ordinary plural. Appendix’s is singular and possessive:

The appendix’s first table contains the results.

Mistake: Using Appendice As The Singular

Incorrect:

See the appendice at the end of the report.

Correct:

See the appendix at the end of the report.

Appendices is plural, but appendice is not its standard English singular form.

Mistake: Mixing Both Plurals In One Document

Inconsistent:

The paper has four appendices, and all four appendixes include graphs.

Consistent:

The paper has four appendices, and all four appendices include graphs.

Choose one form for the same meaning unless a style requirement gives you a reason to change it.

Mistake: Confusing An Appendix With An Addendum

An appendix provides supplementary information related to the main document. An addendum adds material, corrections, or terms after a document has been prepared.

The words can overlap in some situations, but they are not always interchangeable.

Everyday Examples

Examples With Appendices

• The book includes maps in its appendices.
• Please attach the financial statements as appendices.
• The appendices explain how the researchers collected the data.
• Students should review all three appendices before the exam.
• The legal agreement contains several technical appendices.
• Additional photographs appear in the appendices.
• We removed two unnecessary appendices from the final report.
• The dissertation’s appendices include interview transcripts.
• Appendix A and Appendix B are the report’s main appendices.
• The appendices provide evidence supporting the author’s argument.

Examples With Appendixes

• The handbook contains two short appendixes.
• The editors revised all the appendixes before publication.
• Doctors removed the patients’ inflamed appendixes.
• The specimens included several human appendixes.
• Researchers compared the lengths of the appendixes.
• Both appendixes contained similar tissue.
• The new edition has fewer appendixes than the previous one.
• These appendixes provide extra troubleshooting instructions.

A Paired Example

The medical report includes two appendices describing the five appendixes examined during the study.

Here, appendices refers to sections of the report, while appendixes refers to anatomical organs. This contrast is useful for clarity, even though dictionaries accept both plural forms.

Dictionary-Style Word Details

Verb

• Appendixes: Not a verb in this comparison. It is a plural noun.
• Appendices: Not a verb. It is also a plural noun.

The related verb is append, which means to add or attach something:

Please append the chart to the report.

Noun

• Appendixes: A correct plural of appendix. It can describe multiple supplementary sections or multiple anatomical structures.
• Appendices: Another correct plural of appendix. It is especially common for supplementary sections in formal documents.

The singular form of both words is appendix.

Synonyms

Exact replacements depend on the meaning.

For document-related appendixes or appendices, the closest alternatives include:

• Supplements
• Additional sections
• Supporting materials
• Attachments
• Addenda

These alternatives are not exact in every case. For example, an attachment may exist as a separate file, while an appendix usually belongs to the main document.

For anatomical appendixes, there is no simple plural synonym that fits every medical sentence. The more specific term vermiform appendixes may appear in anatomical writing.

Example Sentences

Appendixes:

• The revised guide contains two new appendixes.
• Doctors examined the removed appendixes.
• All three appendixes include practical exercises.

Appendices:

• The report’s appendices contain supporting evidence.
• We shortened the appendices before publication.
• Refer to Appendices A and B for the full calculations.

Word History

Appendix entered English from Latin, where it referred to something attached or added. That history explains the Latin-style plural appendices.

Over time, English speakers also formed appendixes by applying the regular English plural ending. As a result, modern dictionaries accept both forms.

The history explains the variation, but it does not make one form universally correct and the other incorrect.

Phrases Containing

Appendixes:

• Anatomical appendixes
• Inflamed appendixes
• Removed appendixes
• Several appendixes
• Document appendixes

Appendices:

• Supporting appendices
• Technical appendices
• Report appendices
• Book appendices
• Included in the appendices
• Refer to the appendices
• Appendices A through C
• Tables and appendices

Frequently Asked Questions

Conclusion

Both appendixes and appendices are correct plurals of appendix. Therefore, the choice is not simply between a correct spelling and an incorrect one.

Use appendices for supplementary sections in books, reports, research papers, and other formal documents. Use appendixes when discussing multiple anatomical organs or when following the regular English plural pattern.

Most importantly, follow any required style guide and remain consistent. If no special guidance applies, remember this practical preference: documents usually have appendices, while bodies can have appendixes.