Choosing between appendixes and appendices can be confusing because both spellings are correct. The difference is not simply that one is right and the other is wrong. Instead, the best choice often depends on what you are describing.
Both words are plural forms of appendix. However, appendices is commonly used for additional sections at the end of books, research papers, and reports. Meanwhile, appendixes is especially common when referring to the anatomical body part.
Understanding this distinction can help you choose the right form for a school assignment, professional report, medical discussion, or other piece of writing.
For most academic documents, appendices is a reliable choice when referring to supplementary material. If you are discussing the body’s anatomical structures, appendixes is a common choice. Both forms are recognized, so context and any required style guide should guide your decision.
Quick Answer
Appendixes and appendices are both correct plural forms of appendix.
Use appendices when referring to supplementary sections at the end of a book, research paper, report, or other document. Use appendixes when referring to multiple anatomical appendixes, such as in a medical discussion.
Here are two examples:
- The research paper includes three appendices containing survey results.
- The medical team discussed the patients’ appendixes.
The first sentence refers to extra written material. The second refers to body parts.
These are useful general preferences, not an absolute rule that makes the other form incorrect in every context. If a publisher, university, or organization specifies one form, follow that guidance and use it consistently.
Why People Confuse Them
The confusion occurs because English permits more than one plural form for this word. One form follows a traditional pattern associated with Latin, while the other uses a familiar English plural ending.
The singular word is appendix. To form the plural, writers may use either appendices or appendixes.
The endings also look and sound different. Appendices ends in -ices, while appendixes ends in -ixes. Because many readers encounter appendices in academic writing, they may assume that appendixes is incorrect.
That assumption is too strict. The two forms are accepted, although their typical uses can differ.
Another source of confusion is that the word appendix has more than one meaning. It can refer to an additional section of a document or to a small anatomical structure connected to the large intestine. The preferred plural may depend on which meaning you intend.
Key Differences At A Glance
| Context | Best Choice | Why |
|---|---|---|
| Research paper | Appendices | Common form for supplementary material |
| College thesis | Appendices | Familiar in academic writing |
| Book with extra sections | Appendices | Standard editorial choice in this context |
| Medical discussion | Appendixes | Common plural for the anatomical meaning |
| General writing | Either | Both forms are accepted |
| Required house style | Follow the guide | Consistency is important |
A Simple Spelling Comparison
- Appendices: The traditional plural form, commonly used for supplementary sections in documents.
- Appendixes: The regular English plural form, commonly used for the anatomical meaning.
Both words refer to more than one appendix. Neither spelling is universally wrong.
Are They the Same Word?
Yes. Appendices and appendixes are plural forms of the same singular noun, appendix.
When the word refers to supplementary material, it describes information placed after the main text. This material may include questionnaires, detailed calculations, supporting tables, research notes, or additional documents.
For example:
“The report contains two appendices with supporting data.”
When the word refers to anatomy, it describes the small pouch connected to the large intestine.
For example:
“The doctors examined the patients’ appendixes.”
The two plural forms do not represent separate words with unrelated meanings. Instead, they are different ways of forming the plural of the same noun.
Pronunciation also differs slightly. Appendices is commonly pronounced “uh-PEN-dih-seez,” while appendixes is commonly pronounced “uh-PEN-dik-siz.” These guides are approximate, but they can help you recognize the difference when listening to a presentation or conversation.
US vs UK Preference
Both appendices and appendixes are recognized in American and British English. There is no simple rule that assigns one spelling exclusively to the United States and the other to the United Kingdom.
The meaning of the word matters more than the country.
For supplementary sections in books and reports, appendices is a familiar and widely used choice in both varieties of English. For the anatomical meaning, appendixes is commonly used, although the alternative plural is also recognized.
Academic institutions and publishers may have their own preferences. A research journal might specify how supplementary sections should be named, while a medical publication may follow a different editorial convention.
When writing for an American audience, you can confidently use appendices for document sections and appendixes for anatomical references. Just remember that these are practical preferences rather than rigid regional spelling rules.
Which Spelling Should You Use?
The easiest way to choose is to identify what you mean by appendix.
For a school paper, dissertation, business report, or book, appendices is usually the most natural choice. It is widely familiar in formal writing and clearly signals additional material at the end of a document.
For anatomical discussions, appendixes is a common choice. For example, a medical report might discuss the condition of several patients’ appendixes.
Consider these examples:
- Academic writing: The dissertation includes four appendices.
- Business writing: Please review Appendices A and B before the meeting.
- Medical writing: The study examined differences in the patients’ appendixes.
If your university requires a particular form, follow its instructions. The same advice applies to publishers, journals, and professional organizations.
Most importantly, do not switch between the two forms without a reason. Consistency makes your writing easier to read and edit.
When One Spelling Looks Wrong
Writers sometimes assume that appendixes is incorrect because appendices looks more formal. Others may believe that appendices is unnecessarily complicated because appendixes follows a familiar English pattern.
Neither assumption is accurate.
Both forms are accepted plural spellings. The fact that one is more common in a particular context does not automatically make the other a mistake.
For example, this sentence is correct:
“The report contains three appendices.”
This sentence is also correct:
“The report contains three appendixes.”
The first is a familiar choice for supplementary document sections. The second is also a valid plural, although appendices is often preferred in that context.
When you see either form, consider the meaning and the writing style before deciding whether a correction is needed.
Common Mistakes (and Quick Fixes)
Mistake 1: Assuming Appendixes Is Always Wrong
Incorrect assumption: “Appendixes is never a correct word.”
Correction: Both appendixes and appendices are accepted plural forms.
Quick fix: Learn the usual context for each form instead of memorizing an absolute rule.
Mistake 2: Using Appendixes in Every Academic Document
Less natural in many academic contexts: “The dissertation contains three appendixes.”
Common academic choice: “The dissertation contains three appendices.”
The first sentence is not automatically grammatically wrong. However, the second often sounds more familiar in formal academic writing.
Quick fix: Use appendices for supplementary sections unless your institution or publisher prefers another form.
Mistake 3: Treating the Forms as Different Singular Words
Incorrect: “Appendices is the singular, while appendixes is the plural.”
Correct: Appendix is singular. Both appendices and appendixes are plural.
Quick fix: Remember the relationship: one appendix, multiple appendices or appendixes.
Mistake 4: Switching Between Forms Without a Reason
Inconsistent: “The report includes two appendices. The appendixes provide additional charts.”
Improved: “The report includes two appendices. The appendices provide additional charts.”
Quick fix: Choose one plural form for the same document meaning and use it consistently.
Mistake 5: Ignoring the Intended Meaning
A document’s supplementary sections and an anatomical body part do not always favor the same plural form.
Quick fix: Check whether you are discussing written material or anatomy before choosing the plural.
Everyday Examples
The following examples show how each form appears in natural American English.
Examples Using Appendices
- The research paper includes three appendices.
- Additional survey questions appear in the appendices.
- Please review Appendices A and B before submitting your report.
- The dissertation’s appendices contain interview transcripts.
- Supporting calculations are included in two appendices.
- The editor asked us to shorten the appendices.
- Readers can find the detailed results in the appendices.
- Each appendix contains information that supports the main discussion.
- The final chapter refers readers to the appendices.
- Our report includes appendices with charts and supporting documents.
Using Appendixes
- The medical discussion covered the patients’ appendixes.
- Researchers compared findings involving the patients’ appendixes.
- The article explains the anatomical structure of the appendixes.
- Several appendixes were examined during the study.
- The medical report discusses conditions affecting the appendixes.
Showing Both Forms
- Book: The author added two appendices to explain the research.
- Business report: Three appendices provide additional financial information.
- Medical context: The discussion concerns the patients’ appendixes.
- Academic assignment: Label each supplementary section as directed by your instructor.
- Editing: The writer checked every reference to the appendices for consistency.
The examples illustrate common preferences, not an absolute ban on either plural form.
Dictionary-Style Word Details
Verb
Appendices: Not a verb. It is a plural noun.
Appendixes: Not a verb. It is also a plural noun.
Neither spelling functions as a standard verb in this comparison.
Noun
Appendices: The plural of appendix, especially familiar when referring to supplementary material at the end of a book, report, or research paper.
Example: The appendices contain the full survey results.
Appendixes: Also a plural of appendix, commonly used for the anatomical body part.
Example: The medical team discussed the patients’ appendixes.
Both forms are nouns. Their preferred use depends on context and editorial convention.
Synonyms
When appendix refers to additional material in a document, the closest plain alternatives include:
- Supplement: Additional material that supports or extends a main work.
- Addendum: Additional information or material added to a document.
- Attachment: A separate item included with a document or message.
These words have related meanings but are not exact substitutes in every situation.
For the anatomical meaning, there is no direct everyday synonym that fits all contexts.
Appendices and appendixes do not have separate synonym lists because they are alternative plural forms of the same noun.
Example Sentences
- The appendices contain the complete survey questionnaire.
- Two appendixes were discussed in the anatomical study.
- The professor requested that the appendices follow the main chapters.
- Please check the appendixes section before the report is finalized.
- Appendix A contains the questionnaire, while Appendix B contains the results.
The last example uses the singular form in each label because it identifies individual sections. When referring to several such sections collectively, either accepted plural form may be used as appropriate.
Word History
The word appendix comes from Latin appendere, meaning “to hang upon” or “to attach.” Its history helps explain why English has the traditional plural appendices.
Over time, English also developed the regular plural appendixes, using the familiar -es ending.
This gives the language two established plural forms. The difference reflects how borrowed words can retain traditional forms while also following ordinary English patterns.
The historical background explains why the spellings differ, but it does not make one form universally correct and the other incorrect.
Phrases Containing
Common phrases and expressions include:
- Appendices to a report: Supplementary sections attached to a report.
- Appendices of a dissertation: Additional material at the end of a dissertation.
- Appendices A and B: Two separately labeled supplementary sections.
- Supporting appendices: Sections containing evidence or additional information.
- Medical appendixes: Multiple anatomical appendixes discussed in a medical context.
- Appendix section: The part of a document containing supplementary information.
Use the plural that best fits the meaning and follow any required publication style.
FAQs
Is it appendixes or appendices?
Both appendixes and appendices are correct plural forms of appendix. When referring to extra sections in a book, report, or academic paper, appendices is commonly preferred.
What is the plural of appendix?
The plural of appendix can be appendixes or appendices. Both forms are accepted in English, although the preferred form may depend on the context and style guide.
Are appendices and appendixes the same thing?
Yes. Both words are plural forms of appendix. When they refer to supplementary sections in a document, they have the same basic meaning.
Should I use appendices or appendixes in academic writing?
Appendices is a common choice in academic writing, research papers, theses, and formal reports. However, appendixes is also correct. Follow your institution’s style guide and use one form consistently.
Is appendices more formal than appendixes?
Appendices often appears in formal and academic writing, so it may sound more familiar in those settings. However, appendixes is not incorrect or inherently informal.
Is appendixes grammatically correct?
Yes. Appendixes is a grammatically correct plural form of appendix. It is especially common when discussing anatomical structures, although usage can vary by dictionary and context.
What is the difference between appendixes and appendices in anatomy?
When referring to the small organs attached to the large intestine, appendixes is the usual plural form in many dictionaries. Appendices may also be encountered, but appendixes is a clear choice for anatomical writing.
Is appendices the British spelling and appendixes the American spelling?
No. The difference is not simply American versus British English. Both forms are used in English, including American English. The context and the preferred style guide matter more than regional spelling rules.
How do you pronounce appendices and appendixes?
Appendices is commonly pronounced “uh-PEN-dih-seez,” while appendixes is commonly pronounced “uh-PEN-dik-siz.” Pronunciation may vary slightly by speaker and dictionary.
Can I use appendices and appendixes in the same document?
You can, but it is usually better to choose one form and use it consistently when referring to the same kind of supplementary material. Consistency helps readers follow your document and keeps your writing polished.
Conclusion
Both appendixes and appendices are correct plural forms of appendix. The main difference is their typical use, not a simple distinction between correct and incorrect spelling.
For supplementary sections in academic papers, books, and reports, appendices is usually the more familiar choice. For the anatomical body part, appendixes is commonly used.
American and British English recognize both forms, although dictionaries describe preferences that depend on meaning. A university, publisher, or organization may also specify a preferred form.
Remember the singular first: appendix. When you need the plural, choose appendices or appendixes according to context, and remain consistent throughout your writing.
