Choosing between appendices and appendixes often confuses writers, editors, and students alike. Both terms refer to the plural form of appendix, but their usage depends on context, tone, and audience. In formal and academic writing, appendices is generally preferred, especially in research papers, theses, dissertations, and scientific documents. This form follows Latin pluralization rules, which many style guides and scholarly institutions still favor. On the other hand, appendixes is more common in modern English usage, particularly in technical manuals, medical contexts, and everyday writing where clarity and simplicity matter more than tradition.
Understanding the difference between appendices vs appendixes helps ensure your writing aligns with grammar standards, style guide recommendations, and reader expectations. While both plural forms are grammatically correct, choosing the right one can improve professional credibility, readability, and consistency within a document. Writers often wonder which option sounds more natural or authoritative, especially when preparing formal documents or published content.
What Is an Appendix?
An appendix is supplementary material added to the end of a book, report, or academic paper. Its purpose is to provide additional information that supports the main text but would interrupt the flow if included in the main body.
Examples of what an appendix can contain include:
- Raw data from experiments
- Detailed survey results
- Charts and graphs
- Questionnaires or forms
- Additional explanations or technical details
For instance, a research paper on consumer behavior might include a survey questionnaire in the appendix so readers can see the exact questions used. The key is that appendices are supportive, not essential, to understanding the main content but enhance credibility and depth.
Historically, the word appendix comes from Latin appendere, meaning “to hang upon.” The term originally referred to something added to a main document or book, a practice dating back to early manuscripts.
Appendices vs. Appendixes — Are They Both Correct?
Yes, both appendices and appendixes are correct plurals of appendix, but they are used differently.
Appendices is the traditional plural in formal, academic, and professional contexts. It follows the Latin pattern, similar to words like alumnus → alumni or cactus → cacti.
Appendixes is the Anglicized plural, more commonly used in casual American English writing or when Latin-style plurals feel overly formal.
| Plural Form | Usage Context | Notes |
| Appendices | Academic, professional, formal | Preferred in APA, Chicago, and Oxford style guides |
| Appendixes | Casual, informal, some US texts | Acceptable in less formal documents |
Merriam-Webster recognizes both forms, but notes that appendices is considered the “preferred plural.”
When to Use Appendices
Appendices are typically used in formal writing when you want to:
- Include supplementary data
- Avoid cluttering the main text with complex tables or graphs
- Provide transparency and allow readers to verify sources
Examples:
- In a thesis, appendices might include interview transcripts or detailed calculations.
- In a business report, they could house financial statements or expanded market analysis.
- In a technical manual, an appendix might show additional schematics or specifications.
Formatting tips for appendices:
- Label each appendix clearly: “Appendix A,” “Appendix B,” etc.
- Start each appendix on a new page.
- Include a title or brief description at the top.
- Reference the appendix in the main text: “(see Appendix A for detailed results).”
By following these rules, readers can easily navigate between your main content and supporting materials.
When to Use Appendixes
Appendixes is less formal but still correct in certain contexts. You might encounter it in:
- Non-academic books
- Casual reports
- Articles or blogs that prefer Anglicized plurals
In practical terms, using appendixes rarely leads to misunderstanding, but it may appear less professional in scholarly writing.
Comparison table: Appendices vs. Appendixes in context
| Sentence Example | Recommended Plural |
| “All raw data is provided in the appendices.” | Appendices |
| “See the appendixes for additional charts.” | Appendixes |
| “Appendices include survey results and graphs.” | Appendices |
| “The appendixes contain extra explanations.” | Appendixes |
Consistency is key. Pick one plural form and stick with it throughout the document.
Style Guide Recommendations
Different style guides have distinct preferences:
| Style Guide | Preferred Plural | Notes |
| APA (7th edition) | Appendices | Always capitalize and label sequentially |
| MLA (9th edition) | Appendices | Use for research papers and literary analysis |
| Chicago Manual of Style | Appendices | Recommended for books and manuscripts |
| Oxford English Dictionary | Appendices | Formal English usage |
| Harvard Style | Appendices | Common in academic writing |
In almost all formal contexts, appendices is the safe choice. Using appendixes might be acceptable for US-style casual reports, but academic or professional documents should stick to the Latin plural.
Pronunciation and Common Mistakes
Both plurals are pronounced differently:
- Appendices: /ə-ˈpen-də-seez/
- Appendixes: /ə-ˈpen-dik-siz/
Common mistakes to avoid:
- Mixing singular and plural: “The appendix include…” should be “The appendices include…”
- Using appendices in singular form incorrectly: “Appendices A shows…” → “Appendix A shows…”
- Switching between appendices and appendixes in the same document
Tip: Read your sentences out loud. If it sounds awkward, revise. A consistent plural makes your writing professional and credible.
Examples in Sentences
Here are practical examples of correct usage for both forms:
Appendices (formal):
- “The study’s raw data is provided in the appendices.”
- “Appendices A and B contain the full interview transcripts.”
- “Refer to the appendices for supplementary charts and graphs.”
Appendixes (informal/Anglicized):
- “See the appendixes for additional illustrations.”
- “The appendixes include extra notes for casual readers.”
Case study example:
A 2023 academic paper on climate change used appendices to include:
- Full temperature datasets spanning 50 years
- Maps showing regional variations
- Survey questionnaires
This allowed the main text to remain concise while providing transparency.
Conclusion
The choice between appendices and appendixes ultimately depends on context, audience, and writing style. Both forms are grammatically correct and accepted in modern English. However, appendices is typically preferred in academic writing, research papers, and formal documents because it follows traditional Latin pluralization rules. In contrast, appendixes is more commonly used in technical writing, medical texts, and general usage, where clarity and straightforward English take priority. To maintain consistency and professional tone, always follow the relevant style guide—such as APA, MLA, or Chicago—and stick to one form throughout your document. When used correctly, either plural enhances clarity, readability, and credibility in your writing.
FAQs
Are appendices and appendixes both correct?
Yes, both appendices and appendixes are correct plural forms of appendix and are widely accepted in English.
Which is more formal: appendices or appendixes?
Appendices is considered more formal and is commonly used in academic and scholarly writing.
Which plural does APA style recommend?
APA style generally prefers appendices, especially in research papers and academic publications.
Is appendixes used in academic writing?
While not wrong, appendixes is less common in academic contexts and is more often seen in technical or general writing.
Should I use both in the same document?
No. For clarity and consistency, choose one plural form and use it throughout your document.
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