Have you ever reached the end of a report or research paper and seen a section called Appendices? Then, somewhere else, you may have noticed Appendixes instead.
At first, these two forms can look like a spelling mistake. They are not.
Both appendices and appendixes are accepted plural forms of the noun appendix.
The interesting part is that the two forms are not always used in exactly the same way. In modern English, appendices is especially common when talking about extra sections at the end of a book, report, thesis, or other document.
Appendixes is also correct and is widely used, especially as a regular English plural. Dictionaries such as Merriam-Webster and Cambridge list both forms for the book or document sense.
Oxford notes that appendices is usually preferred for a section in a book or document, while appendixes is usually used for the body part.
That small difference causes a lot of confusion for students, writers, and even native speakers.
You may also wonder how to pronounce these words, whether one is more formal, whether appendixes is wrong, and which form you should use in a school assignment or academic paper.
The good news is that the basic idea is simple. Once you understand what appendix means and why English has two plural forms, the choice becomes much easier.
This guide explains both forms with clear examples, grammar rules, common mistakes, easy memory tricks, and everyday examples.
By the end, you will know exactly when to use appendices, when appendixes is perfectly fine, and how to avoid common errors.
What Does “Appendices” Mean?
Appendices is one of the plural forms of appendix.
An appendix is an extra section placed at the end of a book, report, research paper, thesis, legal document, or similar piece of writing. It usually contains information that is useful but too detailed to place in the main part of the document.
When there is more than one such section, we use appendices.
For example:
- The report contains three appendices.
- Please see the appendices for the full survey results.
- The researcher included two appendices with extra data.
- The appendices contain copies of the questionnaires.
- You can find the complete tables in the appendices.
- The thesis has four appendices at the end.
- Several appendices provide additional information.
- The teacher asked us to read the appendices before the exam.
The word is pronounced roughly like uh-PEN-di-seez.
When Should You Use “Appendices”?
Use appendices when you are talking about two or more additional sections attached to a written document.
This form is especially common in academic, professional, and formal writing. You will often see it in research papers, university theses, business reports, books, manuals, and official documents.
For example:
The research findings are explained in the main report, while the detailed calculations are included in the appendices.
The main information is in the report, but the supporting material has been moved to separate sections at the end.
Another example:
The book includes three appendices covering historical dates, maps, and statistics.
Here, appendices clearly means more than one extra section.
The Grammar Rule Behind “Appendices”
The singular noun is:
appendix
The plural can become:
appendices
This is an example of a traditional Latin-based plural. English has borrowed many words from Latin, and some of them still keep older plural forms.
You may have seen similar patterns with words such as:
- analysis → analyses
- crisis → crises
- thesis → theses
- basis → bases
So:
one appendix → two appendices
Not:
one appendix → two appendix
And not:
one appendix → two appendixs
Those forms are incorrect.
A Common Learner Confusion
Many students think appendices must be the only correct plural because it looks more academic.
That is not completely true.
Appendices is certainly correct, but appendixes is also a legitimate plural form. Major dictionaries recognize both forms. Merriam-Webster lists appendixes or appendices, while Cambridge also gives both for the book/document meaning.
So, if you write appendixes, you have not automatically made a spelling error.
The important question is often style and context, not simply right versus wrong.
What Does “Appendixes” Mean?
Appendixes is the other accepted plural form of appendix.
It follows the normal English plural pattern: add -es to the singular word ending in x.
So:
appendix + es = appendixes
It is pronounced roughly like uh-PEN-dik-siz.
Examples include:
- The book has two appendixes.
- The editor checked all the appendixes before publication.
- The appendixes contain useful reference material.
- The report includes several appendixes.
- We added the charts to the appendixes.
- The final chapter refers readers to the appendixes.
- The publisher requested shorter appendixes.
- The student forgot to number the appendixes.
Cambridge and Merriam-Webster both recognize appendixes as a valid plural. Merriam-Webster specifically gives appendixes or appendices as the plural of appendix, and Cambridge provides examples of appendixes used for books and other written works.
When Should You Use “Appendixes”?
You can use appendixes when you mean multiple appendices or extra sections at the end of a document.
For example:
The handbook contains several appendixes with technical information.
This sentence is grammatically correct.
You may also see appendixes used for the anatomical sense of appendix, meaning the small tube-shaped body part attached to the large intestine.
For example:
The doctors compared the patients’ inflamed appendixes.
Oxford specifically notes that appendixes is usually the plural used for the body-part meaning, while appendices is usually used for the book or document meaning.
However, this distinction is not an absolute rule across all forms of English. Merriam-Webster lists both plural forms more generally, and Cambridge also accepts both for the written-material sense.
Why Does “Appendixes” Look Strange?
Some learners expect appendix to change completely because they have learned Latin plurals.
They see:
appendix → appendices
and think:
appendix → appendixes
must be wrong.
But English often has more than one accepted plural form, especially with words borrowed from other languages.
Over time, English speakers sometimes create a regular English plural alongside an older traditional form. That is what happened here.
In simple terms:
appendices = traditional plural
appendixes = regular English plural
Both can be correct, depending on context, style, and meaning.
Difference Between Appendices and Appendixes
The most important point is this:
Appendices and appendixes are both plural forms of appendix.
They usually have the same basic meaning when they refer to extra sections at the end of a written work.
The difference is mainly about usage preference and context.
| Feature | Appendices | Appendixes |
|---|---|---|
| Singular form | appendix | appendix |
| Plural form | appendices | appendixes |
| Meaning | More than one appendix | More than one appendix |
| Pronunciation | uh-PEN-di-seez | uh-PEN-dik-siz |
| Used for books/reports | Very common | Also correct |
| Used in academic writing | Very common | Correct, depending on style |
| Used for body parts | Less usual | Usually preferred |
| Grammar status | Correct plural | Correct plural |
Usage Difference
For books, reports, research papers, and academic documents, appendices is often the form you will see most frequently.
For example:
The statistical tables are included in the appendices.
This sounds completely natural in academic English.
But:
The statistical tables are included in the appendixes.
is also grammatically acceptable.
Oxford recommends appendices as the usual form for the book/document meaning and appendixes for the body-part meaning.
So, if you are writing a university thesis, appendices is often the safest traditional choice unless your school or style guide says otherwise.
Grammar Logic
The word appendix comes from Latin, and appendices reflects a traditional Latin plural pattern. Merriam-Webster traces the word to Latin appendix, from a form related to appendere, meaning to attach or hang something onto something else.
But English does not always preserve foreign plural patterns.
Speakers often make borrowed words fit normal English grammar. That is why appendixes developed and became accepted.
So English now has two paths:
appendix → appendices
and
appendix → appendixes
You do not need to memorize the history to use the word correctly. Just remember that both forms are accepted.
Sentence Structure
There is no difference in sentence structure between the two words.
Both can be used as plural countable nouns.
For example:
The appendices are at the end of the report.
The appendixes are at the end of the report.
Because both nouns are plural, they normally take plural verbs.
Correct:
The appendices are useful.
The appendixes contain extra tables.
Incorrect:
The appendices is useful.
The same grammar applies to other plural nouns.
Meaning Comparison
For written documents:
appendix = one extra section
appendices / appendixes = two or more extra sections
Example:
The report has one appendix.
More than one:
The report has three appendices.
Or:
The report has three appendixes.
Both plural forms can be correct.
The difference is not that one means “extra information” and the other means something completely different. The distinction is mostly traditional versus regular plural usage and, in some dictionaries, the context in which the word is used.
Grammar Rules You Must Remember
Rule 1: “Appendix” Is Singular
Use appendix when you are talking about one section or one body part.
Examples:
Please read Appendix A.
The report has one appendix.
The patient had an inflamed appendix.
A common mistake is using the plural when the number is one.
Incorrect:
Please see appendices A.
Correct:
Please see Appendix A.
Rule 2: Use “Appendices” or “Appendixes” for More Than One
When there are two or more, use a plural form.
Examples:
The report contains two appendices.
The report contains two appendixes.
Both are grammatically correct for extra sections.
Remember that appendices and appendixes are not singular forms.
Incorrect:
There are three appendix at the end.
Correct:
There are three appendices at the end.
Or:
There are three appendixes at the end.
Rule 3: Follow the Style Guide for Formal Writing
When writing a thesis, dissertation, journal article, business report, or school assignment, consistency matters.
If your university or publisher uses appendices, keep using appendices throughout the document.
Do not write:
Appendix → appendices → appendixes → appendices
when all of the words refer to the same kind of material.
Choose the form preferred by your style guide and stay consistent.
Rule 4: “Appendixes” Is Not Automatically Wrong
This is perhaps the most useful rule for learners.
Do not correct someone just because they wrote appendixes.
Major dictionaries accept it. Merriam-Webster gives both appendixes and appendices as plural forms, and Cambridge also recognizes both for written material.
If you are writing in a formal academic setting, appendices may be the more traditional and widely preferred choice.
But appendixes is a real English word.
Common Mistakes Students Make
Many errors happen because learners try to apply one simple plural rule to every word.
Mistake 1: Writing “Appendixs”
Incorrect:
The report contains three appendixs.
Why is it wrong?
English words ending in x normally form the regular plural with -es, not simply -s.
So the regular plural is:
appendix → appendixes
There is also the traditional plural:
appendix → appendices
Correct:
The report contains three appendices.
or
The report contains three appendixes.
Mistake 2: Thinking Only “Appendices” Is Correct
A student may write:
Is “appendixes” wrong?
No. It is a valid plural.
Cambridge lists appendixes and appendices for the book/document meaning, while Merriam-Webster lists both as plural forms.
The better question is:
Which form fits my context and style?
Mistake 3: Using “Appendices” for One Section
Incorrect:
The appendices contains the results.
Here, the verb contains is singular, but appendices is plural.
Correct:
The appendix contains the results.
Or, if you mean several sections:
The appendices contain the results.
Mistake 4: Mixing Singular and Plural Forms
Incorrect:
There are two appendix at the end.
Correct:
There are two appendices at the end.
Or:
There are two appendixes at the end.
Mistake 5: Changing the Plural in the Same Document
Imagine a research paper that uses:
Appendix A
Appendix B
Appendix C
Later, the writer suddenly says:
See the appendixes for more information.
Then another page says:
More information is available in the appendices.
This is not a major grammar error, but it makes the document look less polished.
Pick one form and use it consistently.
Mistake 6: Assuming Formal Means Correct
Some learners believe:
appendices = correct
appendixes = informal and wrong
That is too simple.
Appendixes is accepted English. The traditional form appendices may feel more natural in academic writing, but the regular plural is not a spelling mistake.
Easy Trick to Remember the Difference
Here is a very easy memory trick.
Think of appendices as the form you will often meet at the end of books and academic documents.
Think:
Book → Appendix → Appendices
For example:
Read the appendices at the end of the thesis.
Now remember that appendixes is the regular English plural.
Think:
Appendix + ES = Appendixes
Just as many English nouns add -es, this form simply follows a regular pattern.
There is another useful trick.
When the word refers to the body part, remember:
Body → appendixes
Oxford says this is the usual plural for the body-part meaning.
So you can remember:
Documents → appendices
Body parts → appendixes
But keep one important warning in mind: this is a helpful preference, not an absolute law. Merriam-Webster accepts both plural forms generally, and Cambridge accepts both for the written-material sense.
For everyday writing, understanding both forms is more important than trying to force a strict rule where English allows variation.
Daily Life Examples
The word appendix is especially common in school, university, office, research, publishing, and medical settings.
Here are natural examples you may hear or read.
Example 1
Teacher: Where can I find the extra charts?
Student: They are in the appendices at the end of the report.
Example 2
Manager: Did you include the customer survey?
Employee: Yes. I added it to one of the appendixes.
Example 3
Student: Do I need to read every page?
Teacher: Read the main chapters first. You can check the appendices for extra details.
Example 4
Editor: The book has too much material at the end.
Writer: I can shorten the appendixes.
Example 5
Student: Where are the full interview questions?
Teacher: Look in Appendix B.
Example 6
Researcher: The complete data tables are not in the main section.
Assistant: They are included in the appendices.
Example 7
Doctor: The patient has problems with both appendixes.
Here, appendixes refers to body parts.
Example 8
Student: Should I call them appendices or appendixes?
Teacher: Both are accepted, but check the style guide for your assignment.
Example 9
Publisher: Please number each section clearly.
Author: I have labeled the three appendices A, B, and C.
Example 10
Manager: I cannot find the technical specifications.
Employee: They are in the appendix at the end of the manual.
These examples show why context matters. The word appears often in formal writing, but the basic grammar is still simple.
Practice Section
Choose the correct option in each sentence.
1. The report contains three ______ with additional data.
A. appendix
B. appendices
C. appendixs
2. Please see ______ A for the full list.
A. Appendix
B. Appendices
C. Appendixs
3. The book has several ______.
A. appendixes
B. appendix
C. appendixs
4. The doctor examined the patient’s ______.
A. appendices
B. appendix
C. appendixs
5. The extra charts are included in the ______.
A. appendices
B. appendixs
C. appendice
Answers
1. B — appendices
There is more than one extra section, so a plural noun is needed.
2. A — Appendix
The sentence refers to one specific section, “Appendix A.”
3. A — appendixes
This is an accepted plural form.
4. B — appendix
The sentence refers to one body part.
5. A — appendices
The sentence refers to several additional sections in the document.
FAQs
What is the difference between appendices and appendixes?
Both are plural forms of appendix. When talking about extra sections at the end of a book, report, or research paper, both can be correct. Appendices is especially common in formal and academic writing, while appendixes is also a standard English plural.
Is “appendixes” grammatically correct?
Yes. Appendixes is grammatically correct and appears in major dictionaries. Merriam-Webster lists appendixes or appendices as the plural of appendix. Cambridge also gives appendixes as a plural form.
Is “appendices” more formal than “appendixes”?
In many academic and professional contexts, appendices may sound more traditional or formal because it is the older Latin-based plural. That does not make appendixes incorrect. Oxford notes appendices as the usual form for a book or document.
Can I use “appendixes” in an academic paper?
Yes, unless your university, instructor, publisher, or style guide specifically requires another form. Because appendices is very common in academic writing, many writers choose it for consistency with traditional academic usage. The key is to follow the required style and use the same form consistently.
Which is correct: appendices or appendixes?
Both are correct plural forms of appendix. For extra sections in a report or book, appendices is often the preferred traditional form, while appendixes is also accepted. For the anatomical meaning, appendixes is often the usual form according to Oxford.
How do you pronounce appendices and appendixes?
Appendices is pronounced approximately uh-PEN-di-seez.
Appendixes is pronounced approximately uh-PEN-dik-siz.
The pronunciation changes because the endings are different.
Conclusion
Choosing between appendices and appendixes can seem difficult because English gives us two plural forms of the same word. But the basic rule is easy: both forms come from the singular noun appendix, and both are accepted English.
For extra sections at the end of a book, report, research paper, or thesis, appendices is a very common and traditional choice. Appendixes is also correct and is widely recognized as a regular English plural. Dictionaries such as Cambridge and Merriam-Webster support both forms, while Oxford notes that appendices is usually used for documents and appendixes is usually used for the body-part meaning.
The best habit is to focus on the context and follow the style guide you are using.
Remember these simple examples:
one appendix → two appendices
one appendix → two appendixes
And never write appendixs.
Once you see the two forms this way, there is much less to worry about. English sometimes keeps an older plural while also accepting a regular English form. Appendices and appendixes are a perfect example of that.
Evan Rellmont is a writer who turns thoughtful ideas into meaningful words, creating stories and reflections that connect, inspire, and leave a lasting impression.