Have you ever typed a sentence about extra sections in a report and suddenly wondered whether appendixes vs appendices is the correct spelling? 🤔 You are not alone. This is a common English grammar question because appendix has two accepted plural forms, and both can appear in books, research papers, business reports, and other types of writing. The confusion becomes even greater when you see appendices in academic documents but encounter appendixes in other contexts.
The good news is that you do not have to choose between a correct word and an incorrect one. Both appendixes and appendices are accepted plural forms of appendix. The difference is mainly related to traditional versus regular English pluralization, style, context, and personal or editorial preference.
In this guide, we will examine appendixes vs appendices in detail. You will learn what each form means, how to use it correctly, which form is more common in formal writing, what mistakes to avoid, and how to choose the best option for your audience. By the end, this seemingly tricky grammar question should feel much easier. 📚 Favor vs Favour | Themselves vs Theirselves | Leaped vs Leapt
Quick Answer: Appendixes vs Appendices
Appendixes and appendices are both correct plural forms of appendix.
- Appendix = one
- Appendixes = more than one
- Appendices = more than one
For example:
The report contains one appendix.
The report contains several appendixes.
The report contains several appendices.
Therefore, when comparing appendixes vs appendices, neither plural form is automatically incorrect. Appendices is the traditional plural and is especially common in academic and formal writing, while appendixes is the regular English plural.
Understanding the Basics
To understand appendixes vs appendices, start with the singular form: appendix.
An appendix is something added to the end of a larger work. In a book, report, thesis, dissertation, or research paper, an appendix usually contains additional information that supports the main content without interrupting its flow.
For example:
The survey questions are included in the appendix.
If a document contains more than one supplementary section, you can write:
The survey questions are included in the appendices.
Or:
The survey questions are included in the appendixes.
Both sentences are grammatically acceptable.
Comparison Table
| Form | Type | Meaning | Example | Correct/Incorrect |
|---|---|---|---|---|
| appendix | Singular noun | One additional section or anatomical structure | The report has one appendix. | ✅ Correct |
| appendixes | Regular plural | More than one appendix | The report has three appendixes. | ✅ Correct |
| appendices | Traditional plural | More than one appendix | The report has three appendices. | ✅ Correct |
| appendixs | Incorrect plural | Intended to mean multiple appendixes | The report has three appendixs. | ❌ Incorrect |
The most important thing to remember is that appendixes vs appendices is not a battle between right and wrong. Both plural forms are valid.
What Does “Appendix” Mean?
The word appendix has several related uses.
The most common meaning in writing is an additional section placed at the end of a document. It may contain information that is relevant to the subject but too detailed for the main body.
An appendix might include:
- Research data
- Charts
- Tables
- Survey questions
- Interview transcripts
- Technical information
- Calculations
- Supporting documents
- Methodology details
- Additional references
For example:
The researcher included the complete questionnaire in the appendix.
Here, appendix means one additional section.
The word also has a medical meaning. The appendix is a small, tube-shaped structure attached to the large intestine.
For example:
The doctor examined the patient’s appendix.
Because the word has more than one meaning, context tells readers what you mean.
Is “Appendixes” Correct?
Yes. Appendixes is completely correct. ✅
It is the regular English plural of appendix.
The ending -es is added because the word ends in x.
Similar patterns occur in words such as:
- box → boxes
- fox → foxes
- tax → taxes
- appendix → appendixes
For example:
The textbook contains several appendixes.
This sentence is grammatically correct.
Another example:
The company attached two appendixes to the contract.
Again, appendixes is correct.
Why Use “Appendixes”?
Some writers prefer appendixes because it follows a familiar English pluralization pattern. It can also feel more straightforward to readers who prefer regular English plurals.
You may encounter it in:
- Business reports
- Technical documents
- General books
- Medical contexts
- Workplace communication
- Informal writing
However, context and style still matter.
Is “Appendices” Correct?
Yes. Appendices is also correct. ✅
It is the traditional plural form of appendix.
This plural follows the pattern found in several words that entered English from Latin.
Compare:
- appendix → appendices
- analysis → analyses
- thesis → theses
- crisis → crises
Because of this traditional pattern, appendices is particularly common in scholarly and formal writing.
For example:
The dissertation contains four appendices.
Or:
Additional statistical information is provided in Appendices A and B.
Both sentences are standard English.
What Is the Difference Between Appendixes and Appendices?
The basic meaning is the same.
Both appendixes and appendices mean more than one appendix.
The main difference is the form of the plural:
- Appendixes follows a regular English plural pattern.
- Appendices follows a traditional plural pattern.
This difference does not normally change the meaning.
Compare these sentences:
The report includes three appendixes.
The report includes three appendices.
A reader will understand the same basic idea from both sentences.
The choice often depends on style, audience, and context.
A Simple Comparison
Appendixes
- Regular English plural
- Correct
- Straightforward
- Used in various types of writing
Appendices
- Traditional plural
- Correct
- Very familiar in academic writing
- Common in formal documents
So, if someone tells you that appendixes is always wrong, that advice is inaccurate.
Which Form Is More Common in Academic Writing?
In academic writing, appendices is often the more familiar choice.
You are likely to see it in:
- Research papers
- Master’s theses
- Doctoral dissertations
- Academic books
- University reports
- Scientific documents
For example:
The complete interview transcripts are provided in the appendices.
Another example:
The statistical calculations can be found in Appendices A through C.
This does not mean appendixes is grammatically wrong in academic writing. It simply means that appendices has a strong traditional association with formal and scholarly writing.
If your university, professor, journal, or publisher has a specific style guide, follow it.
Academic Example
Imagine you are writing a dissertation about online learning.
Your main chapters discuss your research findings. At the end, you include:
- Appendix A: Survey Questions
- Appendix B: Interview Questions
- Appendix C: Statistical Data
You could introduce these sections by writing:
The research instruments and supporting data are provided in the appendices.
That is a natural choice for academic writing.
Which Form Should You Use in Professional Writing?
Professional writing is slightly more flexible.
Suppose you are preparing a business report containing several supplementary sections.
You could write:
Please review the appendices before the meeting.
You could also write:
Please review the appendixes before the meeting.
Both forms are grammatically correct.
However, consistency matters.
If your company normally uses appendices, use appendices throughout the document. If your company’s established style uses appendixes, keep using that form.
Professional Writing Tip
Before choosing a plural form, check:
- Your company’s style guide.
- Previous reports.
- Your client’s preferred terminology.
- Your publisher’s requirements.
- Any instructions from your editor.
Following an established style is often more important than choosing the form you personally prefer.
Correct Meanings and Uses
1. Supplementary Sections in a Report
An appendix often contains supporting information.
Example:
The financial calculations are included in the appendix.
If there are several sections:
The financial calculations are included in the appendices.
Or:
The financial calculations are included in the appendixes.
The choice between the two plural forms does not change the meaning.
2. Research Papers
Academic researchers frequently use appendices to provide detailed supporting material.
For example:
The full survey appears in Appendix A.
If multiple sections exist:
The full surveys appear in Appendices A and B.
This is one reason appendices is so familiar to students and researchers.
3. Books
A nonfiction book may have supplementary material at the end.
For example:
The author included an appendix explaining the research methods.
A book with multiple supplementary sections might contain:
Several appendices with additional historical information.
4. Legal and Business Documents
Contracts, reports, and proposals may contain supporting sections.
For example:
The pricing information is included in the appendices.
In these contexts, the traditional plural can sound particularly natural.
5. Anatomical Usage
The word appendix can also refer to the organ attached to the large intestine.
For example:
The patient’s appendix was inflamed.
When referring to multiple anatomical appendixes, appendixes can be used.
The context usually makes the meaning clear.
Test Tip: How to Choose the Correct Form
If you are unsure about appendixes vs appendices, use this three-step test.
Step 1: Ask How Many?
If you mean one:
appendix
If you mean more than one:
appendixes / appendices
Step 2: Consider Your Audience
Ask whether your writing is:
- Academic
- Professional
- Technical
- Casual
- Creative
Formal academic writing may naturally favor appendices, while general writing can comfortably use appendixes.
Step 3: Check the Style Guide
If you are writing for an organization or publication, use its preferred form.
Easy Memory Trick
Think:
One appendix, multiple appendices or appendixes.
And remember:
❌ appendixs
is not a standard plural.
Case Study: A University Research Project
Consider a student named Daniel who is completing a research project.
His 80-page paper includes three supplementary sections:
- Survey Questions
- Interview Transcripts
- Raw Data
Daniel writes:
The supplementary materials are included in the appendices.
His professor understands exactly what he means.
Now imagine another student writing:
The supplementary materials are included in the appendixes.
That sentence is also grammatically correct.
The important difference is not correctness. It is stylistic preference.
If the university’s formatting instructions specifically require appendices, Daniel should use that form.
This example shows why understanding appendixes vs appendices is more useful than memorizing a simplistic rule that one form is always right.
Grammar Rules Explained
Why does English allow two plural forms?
The answer lies partly in the history of the word.
Appendix comes from Latin. Traditional English usage preserved the Latin-derived plural appendices.
Over time, English speakers also began treating the word like an ordinary English noun and formed the regular plural appendixes.
This is common in English. Borrowed words sometimes keep older plural forms while also developing regular English plurals.
As a result, dictionaries recognize both forms.
Merriam-Webster lists appendixes and appendices as plural forms of appendix. Cambridge also recognizes both plural forms in its American English dictionary entry.
Therefore, the grammar rule is:
Both appendixes and appendices are accepted plural forms of appendix.
The incorrect form is:
❌ appendixs
English does not normally form the plural that way.
Why Does “Appendices” Sound More Formal?
The reason is largely historical and conventional.
Because appendices follows a traditional Latin-based plural pattern, it has become strongly associated with academic and technical writing.
For example:
The methodology is explained in the appendices.
This sentence sounds natural in a dissertation.
However:
The methodology is explained in the appendixes.
is still grammatically correct.
The perceived difference is mostly stylistic.
This is an important lesson about English: a word can have more than one correct form without the forms having different meanings.
Common Mistakes
Mistake 1: Using “Appendixs”
Incorrect:
The report contains three appendixs.
Correct:
The report contains three appendixes.
Or:
The report contains three appendices.
Mistake 2: Treating “Appendices” as Singular
Incorrect:
This appendices contains the survey.
Correct:
This appendix contains the survey.
Because appendices is plural, it requires a plural verb when appropriate.
For example:
The appendices contain additional information.
Mistake 3: Using a Plural Verb With “Appendix”
Incorrect:
The appendix contain additional information.
Correct:
The appendix contains additional information.
Mistake 4: Mixing Styles
A writer may use appendices in one section and appendixes in another without any clear reason.
This is not necessarily a grammar error, but it can make a document look inconsistent.
Choose one form and use it consistently when possible.
Why Do These Mistakes Happen?
Fast Typing
People often type quickly and may automatically write:
appendixs
because they are thinking about the regular plural ending rather than the spelling.
Autocorrect
Spell-checking software may not always provide the explanation a writer needs. It may also fail to recognize a context-dependent choice.
Lack of Knowledge
Many people learn appendices but never learn that appendixes is also accepted.
Others may encounter appendixes first and assume that appendices is a spelling mistake.
Overreliance on Sound
Because the two plural forms sound different, writers may assume that one must be incorrect.
In reality, English has many words with multiple accepted forms.
Similar Grammar Confusions
The appendixes vs appendices question is similar to many other English language questions where two forms are easy to confuse.
| Common Confusion | Correct Forms | Key Difference |
|---|---|---|
| its vs. it’s | its / it’s | Possessive vs. contraction |
| your vs. you’re | your / you’re | Possessive vs. “you are” |
| their vs. they’re | their / they’re | Possessive vs. “they are” |
| affect vs. effect | affect / effect | Usually verb vs. noun |
| advice vs. advise | advice / advise | Noun vs. verb |
| then vs. than | then / than | Sequence/time vs. comparison |
| appendix vs. appendices | appendix / appendices | Singular vs. plural |
| appendix vs. appendixes | appendix / appendixes | Singular vs. regular plural |
The solution is always the same: understand how the word functions in the sentence.
Usage in Different Contexts
Everyday Conversation
In casual conversation, either plural may be understood.
For example:
Does the book have any appendices?
Or:
Does the book have any appendixes?
Both communicate the intended meaning.
However, people may avoid the technical term entirely and simply say:
Does the book have any extra sections?
Professional Writing
In professional writing, appendices is a common choice.
Example:
Please review the appendices before approving the proposal.
However, appendixes remains correct.
Academic Writing
Appendices is particularly common in:
- Theses
- Dissertations
- Research papers
- Academic reports
- Scholarly books
Example:
The complete research instruments are included in the appendices.
Creative Writing
Creative writers can choose either form according to style.
For example:
The manuscript contained several mysterious appendices.
Or:
The old document had several unusual appendixes.
The writer’s voice and intended audience can influence the choice.
Social Media and Texting
In casual digital communication, people are unlikely to debate the distinction.
For example:
Finally finished my thesis! Three appendices later 😭📚
Or:
This report has five appendixes and I’m finally done!
The important thing in informal communication is that the message remains clear.
Pronunciation Guide
Spelling is not the only difference between these forms. Their pronunciations are also different.
Appendix
Approximately:
uh-PEN-diks
Appendixes
Approximately:
uh-PEN-dik-siz
The ending sounds similar to the ending of boxes.
Appendices
Approximately:
uh-PEN-duh-seez
Knowing the pronunciation can help you recognize both forms when listening to lectures, presentations, or conversations.
Capitalization: Appendix A vs. Appendices
When referring to specific sections of a document, capitalization depends on the document’s style.
For example:
See Appendix A for the survey.
When referring to several labeled sections:
See Appendices A and B for the supporting data.
You may also encounter:
See Appendixes A and B for the supporting data.
Both plural forms remain grammatically possible.
If a document uses numbered or lettered sections, follow the formatting rules established by the institution or publication.
Why It Matters
You might wonder why such a small distinction deserves attention.
The answer is simple: clear writing builds confidence.
Clarity in Communication
Correct word forms make your meaning easier to understand.
Professionalism
A polished report or academic paper demonstrates attention to detail.
Academic Accuracy
Students and researchers frequently need to identify supplementary sections correctly.
Digital Communication
Modern documents are often read quickly on screens. Clear labels help readers navigate information efficiently.
Consistency
Using one accepted form consistently makes your writing feel intentional and professionally edited.
Good grammar helps readers focus on your ideas instead of your mistakes.
That is why learning the difference between appendixes vs appendices is worthwhile even though both forms are correct.
Special Exception: Medical Context
There is one useful contextual distinction worth remembering.
When appendix refers to the anatomical structure, appendixes may be especially straightforward as a regular plural.
For example:
The study examined several patients who had previously had their appendixes removed.
When referring to supplementary sections in a document, appendices is often more familiar in formal writing.
However, this is a matter of usage preference rather than a strict rule that prohibits the other form.
Context helps determine which version feels most natural.
Is “Appendices” American English?
Yes. Appendices is standard in American English.
You do not need to avoid it because it looks Latin-derived.
At the same time, appendixes is also accepted in American English.
Therefore, American writers can use either plural form.
If you are writing for a US audience, the safest general rule is:
Use appendix for one and appendixes or appendices for more than one.
For formal academic documents, appendices is often the more familiar stylistic choice.
Is “Appendixes” Formal Enough?
Yes.
Some writers mistakenly believe that appendixes is too informal for professional or academic writing.
That is not accurate.
Appendixes is a recognized plural form.
Still, readers who frequently work with academic documents may be more accustomed to appendices.
Therefore, if your goal is to match traditional academic style, appendices may be preferable.
If your goal is simply grammatical correctness, appendixes is perfectly acceptable.
How to Choose Between the Two
When deciding between appendixes vs appendices, consider these factors:
Choose “Appendices” If:
- You are writing a thesis.
- You are writing a dissertation.
- You are preparing a research paper.
- Your document is highly formal.
- Your style guide uses traditional plurals.
- Your audience is accustomed to academic terminology.
Choose “Appendixes” If:
- Your style guide prefers regular English plurals.
- Your organization uses the form.
- You are writing general or technical material.
- You want a straightforward regular plural.
- You are discussing multiple anatomical appendixes and the context favors that form.
Remember that these are recommendations about style, not rules about correctness.
Quick Recap Checklist
| Question | If Yes → Use |
|---|---|
| Are you talking about one? | appendix |
| Are you talking about multiple ones? | appendixes or appendices |
| Are you writing a dissertation? | appendices is a natural choice |
| Does your style guide specify a form? | Follow the style guide |
| Is “appendixes” grammatically correct? | Yes |
| Is “appendices” grammatically correct? | Yes |
| Is “appendixs” correct? | No |
| Do you want consistency? | Choose one plural and use it consistently |
Practice Examples
1. The research paper contains three ______.
Possible answers:
appendices
or
appendixes
Both are correct.
2. Please see ______ A for the complete questionnaire.
Correct:
Appendix
Only one section is being identified.
3. The supporting documents are included in the ______.
Possible answers:
appendices
or
appendixes
Both work when referring to multiple sections.
FAQs About Appendixes vs Appendices
1. Is “appendixes” or “appendices” correct?
Both appendixes and appendices are correct plural forms of appendix. Appendices is the traditional plural and is especially common in academic writing, while appendixes is the regular English plural.
2. Is “appendices” more correct than “appendixes”?
No. Neither is inherently more grammatically correct. Appendices may be more traditional or formal in tone, but appendixes is also a standard plural form.
3. What is the singular form of appendices?
The singular form is appendix.
For example:
One appendix
Two appendices
Two appendixes
4. What is the plural of appendix?
The accepted plural forms are appendices and appendixes. Both mean more than one appendix.
5. Should I use appendices in a research paper?
Appendices is an excellent choice for research papers because it is common in academic and formal writing. However, appendixes is also grammatically correct unless your institution or style guide requires appendices.
6. Is “appendixs” a correct spelling?
No. Appendixs is incorrect. The correct plural forms are appendixes and appendices.
Conclusion
The appendixes vs appendices question becomes much easier once you know the central rule: both forms are correct plural forms of appendix. Use appendix when referring to one item, and use either appendixes or appendices when referring to more than one.
The traditional plural appendices is especially common in academic, scholarly, and formal writing. The regular plural appendixes is also accepted and can be a natural choice in general, professional, technical, or medical contexts.
The most important thing is not to treat one form as universally correct and the other as universally wrong. Instead, consider your audience, context, and applicable style guide. Above all, avoid the incorrect spelling appendixs.
So, the next time you wonder about appendixes vs appendices, remember this simple rule: one appendix, two appendixes or appendices—never appendixs. 📚✨
I’m Clara Bennett, a vocabulary and language specialist at Gramfino, where I write about word meanings and proper usage.
I love helping readers choose the right words and build stronger English vocabulary with confidence.
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