Appendixes vs appendices is a common question when writing reports, research papers, books, and other documents. Both forms are correct plurals of appendix, but one is generally more natural in certain contexts.
The main distinction is straightforward: appendices is commonly used for supplementary sections at the end of a document, while appendixes is especially common when referring to the body part. However, these preferences are not absolute rules.
If you are preparing an academic paper, appendices is a familiar choice. If you are discussing human anatomy, appendixes is usually the more natural option. Your intended meaning and any required publication style should guide your decision.
Quick Answer
Both appendixes and appendices are correct plural forms of appendix.
- Use appendices when referring to additional sections in books, reports, research papers, and similar documents.
- Use appendixes most commonly when referring to the small organ attached to the large intestine.
- Both forms can refer to supplementary document sections, so appendixes is not automatically incorrect in formal writing.
For example:
- The research paper includes three appendices.
- The doctors examined the patients’ appendixes.
- The manual contains several appendixes with additional information.
The best choice depends on context. Follow your organization’s style requirements when they specify a preferred form.
What Is Correct?
Neither form is universally wrong. Both are established English plurals of the singular noun appendix.
The word appendix has more than one use. It can refer to an organ in the human body or to a section containing supplementary information at the end of a document.
| Form or Pattern | Best Use | Why |
|---|---|---|
| Appendix | One supplementary section or one body part | Singular noun |
| Appendices | Multiple document sections | Common in academic and formal documents |
| Appendixes | Multiple body parts; also document sections | Accepted plural following the regular English pattern |
The important point is that the two forms are not separated by a strict grammatical boundary. The preference changes with the meaning and the writing context.
The Core Grammar Rule
The rule is simple: appendix has two accepted plural forms, appendices and appendixes.
English forms many plurals by adding -s or -es to a singular noun. That regular pattern explains appendixes. The form appendices follows a different plural pattern associated with the word’s Latin background.
You do not need to memorize a complicated grammatical formula. Instead, remember the two accepted forms and learn where each one is most commonly used.
Both forms take plural verbs when they are the subject of a sentence.
Correct: The appendices contain the complete survey results.
Correct: The appendixes contain the additional diagrams.
Incorrect: The appendices contains the complete survey results.
In the last example, the problem is subject-verb agreement, not the choice between appendices and appendixes.
When Each Form Is Correct
When To Use Appendices
Choose appendices when discussing supplementary sections in academic or professional documents. It is a familiar choice for research papers, dissertations, reports, manuals, and books.
Examples:
- The dissertation includes two appendices.
- Please review the appendices before submitting your report.
- The complete interview questions appear in the appendices.
- Each appendix provides supporting information for the main discussion.
This form is particularly suitable when a school, publisher, or professional organization expects traditional academic conventions.
When To Use Appendixes
Use appendixes when discussing multiple anatomical appendixes. It is a standard and natural plural for the body part.
Examples:
- The medical textbook discusses disorders affecting the appendixes.
- Researchers examined the appendixes of the specimens.
- The report compares observations involving several appendixes.
The form is also acceptable for document sections.
Examples:
- The handbook contains several appendixes.
- The online manual organizes its appendixes by topic.
- Each volume includes appendixes with supplementary details.
If your chosen publication style prefers appendices, follow that preference for documents. Otherwise, appendixes remains a valid option.
When It Is Incorrect or Less Natural
Neither plural is inherently incorrect. However, a form may be less natural for the context or inconsistent with a required style.
For example, this sentence is grammatically acceptable:
“The report contains three appendixes.”
However, appendices may sound more familiar in an academic research paper.
Likewise, appendixes is a natural choice in an anatomical discussion:
“The medical team studied the patients’ appendixes.”
Using appendices in an anatomical context is not automatically ungrammatical, but it may be less typical than appendixes.
Avoid changing between the two forms without a reason. For example, if a report uses appendices throughout, switching to appendixes in one heading can make the document appear inconsistent.
Also remember that appendix is singular. Do not use it when the sentence clearly refers to multiple sections or organs unless the surrounding wording makes the number different.
Meaning, Structure, or Emphasis Differences
The two plurals usually express the same basic idea. The difference is mainly one of conventional usage, not a major change in meaning.
Appendices often signals supplementary material in a written document. Readers commonly encounter it in academic and professional contexts.
Appendixes follows a regular English plural pattern and is particularly familiar in anatomical contexts. It can also refer to supplementary material in books and reports.
Neither form is automatically more intelligent, more professional, or more grammatically advanced. The right choice is the one that fits the context and follows any applicable editorial requirements.
The pronunciation differs as well:
- Appendixes is commonly pronounced uh-PEN-dik-siz.
- Appendices is commonly pronounced uh-PEN-dih-seez.
These pronunciations can help you recognize the forms in conversation, but pronunciation does not determine which plural you should use in writing.
Real-World Examples
Here are practical examples showing how both forms work in everyday American English.
Academic writing
- The professor asked us to include two appendices with our research paper.
- The appendices contain the questionnaire and the complete data tables.
- Please label each appendix clearly in your final submission.
Business and professional documents
- The annual report includes appendices with additional financial information.
- The contract’s appendixes provide supporting schedules.
- Check the document’s required style before finalizing its supplementary sections.
Medical and anatomical contexts
- The textbook explains common conditions affecting the appendix and appendixes.
- The study examined several appendixes for signs of inflammation.
- The doctor explained how an inflamed appendix may require medical treatment.
Everyday writing
- I added two appendices to explain my project.
- The user manual includes appendixes for advanced procedures.
- We moved the extra charts into the appendices to keep the main report focused.
Notice that the surrounding words help readers understand the intended context. The plural form does not change the basic idea of multiple items.
Common Mistakes (and Quick Fixes)
Mistake: Assuming appendixes is always wrong
Incorrect assumption: “Only appendices is acceptable.”
Quick fix: Recognize that both are accepted plurals. Choose according to context and style requirements.
Mistake: Assuming appendices must always be used
Incorrect assumption: “Appendixes is never correct in a report.”
Quick fix: Understand that appendixes can also refer to supplementary document sections.
Mistake: Using inconsistent forms
Unclear: “The report contains three appendices. The appendixes are listed after the references.”
Quick fix: Use one form consistently for the same type of material unless there is a clear reason to change it.
Mistake: Pairing a plural subject with a singular verb
Incorrect: “The appendices contains the survey.”
Correct: “The appendices contain the survey.”
Quick fix: Match the verb to the plural subject.
Mistake: Ignoring a required publication style
Problem: A student uses appendixes when the instructor specifically requires appendices.
Quick fix: Follow the requested convention. A preferred form can be required by a particular style even when another form is generally acceptable.
Grammar Rule Details
Rule
The noun appendix has two accepted plurals: appendices and appendixes. Both are grammatically valid. Usage commonly favors appendices for supplementary document sections and appendixes for anatomical references.
Correct Usage
Use appendices in academic writing when referring to supporting sections at the end of a paper. Use appendixes when referring to multiple anatomical appendixes or when that form is appropriate under your chosen style.
Examples:
- The appendices contain the full survey.
- The patients’ appendixes were examined.
- The handbook includes three appendixes.
Incorrect or Less Natural Usage
Neither plural is automatically incorrect. The less natural choice depends on context, reader expectations, and editorial requirements.
A form can be acceptable English but still conflict with a specific style guide. Always distinguish a preference from a grammatical error.
Examples
- Correct: The report contains two appendices.
- Correct: The report contains two appendixes.
- Correct: The doctors discussed the patients’ appendixes.
- Correct: The appendices provide additional evidence.
- Incorrect: The appendices provides additional evidence.
The final example has an agreement error because appendices is plural.
Common Mistakes
Writers often memorize appendices as the only possible plural because it appears frequently in academic papers. Others assume that adding -es is the only acceptable way to form the plural.
Both assumptions are too restrictive. Learn both forms, understand their usual contexts, and keep your usage consistent.
Exceptions
There is no major exception to memorize. Both plurals are accepted, although their typical contexts differ. A particular publication or institution may require one form.
Quick Test
Ask yourself what you are discussing:
- A research paper, report, or book? Appendices is usually the safest choice.
- Multiple anatomical appendixes? Appendixes is usually the natural choice.
- A document with a specified style? Follow that style.
When both forms are acceptable, consistency is more important than trying to enforce a rule that does not exist.
Usage Notes
Use appendix for one item and either appendices or appendixes for multiple items. In academic writing, check the required format before finalizing your headings and references to supplementary sections.
Remember that plural subjects need plural verbs. For example, “The appendices are included” is correct, while “The appendices is included” is not.
FAQs
Is appendices or appendixes correct?
Both are correct plural forms of appendix. Appendices is commonly preferred for supplementary document sections, while appendixes is especially common for the anatomical sense.
Which form should I use in a research paper?
Use appendices unless your instructor, publisher, or required style guide specifies otherwise. It is a familiar convention in academic writing.
Is appendixes grammatically wrong?
No. Appendixes is an accepted plural. It can refer to anatomical appendixes and can also be used for supplementary sections in documents.
What is the singular of appendices?
The singular is appendix. For example, one document may contain an appendix, while another contains several appendices.
Should I use appendices and appendixes in the same document?
Usually, choose one form and use it consistently for the same context. Follow any applicable style requirements, and avoid switching forms without a clear reason.
Conclusion
Both appendixes and appendices are correct plurals of appendix. The most useful distinction is their usual context: appendices is widely used for supplementary sections in books and academic papers, while appendixes is especially common for the anatomical sense.
For a research paper or formal report, appendices is a reliable default. For anatomical references, appendixes is generally the more natural choice. If your institution or publisher specifies a form, follow that requirement and use it consistently.
