Appendixes or Appendices: Which Is Correct? Meaning & Examples
Appendixes or Appendices: Which Is Correct?
“Appendixes” or “appendices” — which one is correct? If you have ever written a report, research paper, book, academic document, or business report, you may have wondered about the correct plural form of appendix.
The good news is that both “appendixes” and “appendices” are correct plural forms of “appendix.” However, they are not always used in exactly the same way. “Appendices” is generally more common in formal, academic, scientific, and technical writing, while “appendixes” is also grammatically acceptable and may be preferred in some general or modern English contexts.
For example:
- The report contains several appendices. ✅
- The report contains several appendixes. ✅
Both sentences are grammatically correct.
In this article, we will explain the difference between appendixes and appendices, their meanings, pronunciation, usage, singular and plural forms, examples, and which form is generally more appropriate for professional writing.
Appendixes or Appendices: The Short Answer
Both forms are correct:
Appendices ✅
Appendixes ✅
The singular form is:
appendix
The two accepted plural forms are:
appendices
appendixes
However, appendices is traditionally associated with the Latin-derived plural and is particularly common in formal writing.
For example:
The research paper includes three appendices.
You can also write:
The research paper includes three appendixes.
The meaning remains essentially the same.
What Is an Appendix?
Before understanding the plural forms, it helps to understand what an appendix is.
An appendix is a separate section placed at the end of a book, report, academic paper, thesis, dissertation, or other document. It contains additional information that supports the main text but is not essential to understanding the central argument.
An appendix might contain:
- Additional statistics
- Tables
- Charts
- Research data
- Survey questions
- Interview transcripts
- Technical information
- Calculations
- Supporting documents
- Detailed methodology
- Additional references or materials
For example:
The complete survey questions are provided in Appendix A.
If a document contains more than one appendix, they can be labeled:
Appendix A
Appendix B
Appendix C
Collectively, these sections can be called appendices or appendixes.
What Is the Plural of Appendix?
The word appendix has two accepted plural forms:
1. Appendices
Appendices is the traditional plural form and is especially common in academic, scientific, medical, legal, and formal writing.
Example:
The thesis includes four appendices containing additional research data.
2. Appendixes
Appendixes is also a valid English plural.
Example:
The book contains several appendixes with detailed reference material.
Therefore, it is not accurate to say that “appendixes” is always wrong.
Both forms are recognized in standard English.
Why Does Appendix Have Two Plural Forms?
The word appendix comes from Latin. Its traditional Latin plural is appendices.
English has borrowed many words from Latin and Greek, and some of these words have retained traditional plural forms.
However, English also has a strong tendency to form plurals using the regular -s or -es ending.
This has resulted in two forms:
appendix → appendices
and
appendix → appendixes
The same pattern can be found with other borrowed words that have developed both traditional and English-style plural forms.
Appendices vs. Appendixes: Which Is More Common?
Although both are correct, appendices is generally the more familiar choice in formal and academic writing.
You are especially likely to see appendices in:
- University dissertations
- Academic research papers
- Scientific reports
- Government reports
- Legal documents
- Technical manuals
- Professional publications
For example:
The methodology and additional data are explained in the appendices.
However, appendixes can still be used when the writer prefers the regular English plural form.
For general readers, either form can communicate the intended meaning.
Appendices in Academic Writing
In academic writing, appendices is extremely common.
A long research paper may contain information that is useful but too detailed to place in the main body of the paper.
For example:
Appendix A: Survey Questionnaire
Appendix B: Statistical Results
Appendix C: Interview Questions
A sentence in the main text might say:
The complete questionnaire is included in Appendix A.
If multiple sections are being discussed:
Additional research materials are available in the appendices.
Because academic style tends to favor traditional terminology, appendices is often the form readers expect.
Examples of “Appendices”
Here are several examples using appendices:
- The report contains three appendices.
- Additional statistical tables are included in the appendices.
- Please refer to the appendices for supporting information.
- The researcher included several documents in the appendices.
- The thesis has five appendices.
- The complete interview transcripts appear in the appendices.
- Detailed calculations are provided in the appendices.
- The technical specifications can be found in the appendices.
These examples are particularly natural in formal and academic writing.
Examples of “Appendixes”
The regular plural appendixes can also be used correctly.
For example:
- The manual contains several appendixes.
- The book includes two appendixes with additional information.
- The report’s appendixes provide supporting data.
- The technical guide contains detailed appendixes.
- The author added several appendixes to the revised edition.
Although appendixes is less traditional than appendices, these sentences are grammatically acceptable.
Appendices or Appendixes in Formal Writing?
If you are writing a formal academic or professional document and are unsure which form to choose, “appendices” is a safe and widely recognized choice.
For example:
The additional research findings are presented in the appendices.
This sounds natural in a thesis, dissertation, research paper, or formal report.
However, choosing appendixes does not automatically make your writing incorrect.
The most important thing is consistency. If your document uses appendices, continue using that form throughout the document rather than switching between forms without a reason.
Singular vs. Plural: Appendix and Appendices
Here is a simple comparison:
| Number | Form | Example |
|---|---|---|
| Singular | Appendix | See Appendix A for details. |
| Plural | Appendices | See the appendices for details. |
| Plural | Appendixes | See the appendixes for details. |
Remember:
One = appendix
More than one = appendices or appendixes
For example:
Singular:
The researcher added an appendix.
Plural:
The researcher added three appendices.
Is “Appendixes” Grammatically Correct?
Yes. Appendixes is grammatically correct.
Some writers mistakenly believe that only appendices is acceptable because it is the traditional Latin-derived plural.
However, English has adopted appendixes as a standard plural form as well.
Therefore:
appendices ✅
and
appendixes ✅
are both acceptable.
The choice often depends on writing style, field, audience, and personal preference.
Is “Appendices” Always Better?
Not necessarily.
For academic and highly formal writing, appendices is often the more conventional choice. But this does not mean that appendixes is grammatically inferior.
If a particular publication, university, company, or style guide specifies a preferred form, follow that style guide.
For example, if your university’s formatting instructions consistently use appendices, use appendices throughout your thesis.
The key principle is:
Follow the style requirements of your specific document or publication when they exist.
Common Mistakes With Appendix
One common mistake is assuming that the plural must always be formed by simply adding -s:
appendixs ❌
That spelling is incorrect.
The accepted plural forms are:
appendices ✅
appendixes ✅
Another mistake is using appendix when referring to multiple sections:
The report contains three appendix. ❌
Correct:
The report contains three appendices. ✅
or:
The report contains three appendixes. ✅
How to Pronounce Appendices
The pronunciation of appendices is approximately:
uh-PEN-di-seez
The pronunciation of appendixes is approximately:
uh-PEN-dik-siz
Both refer to multiple appendices or supplemental sections.
The pronunciation difference can help explain why the two forms may sound noticeably different even though they have the same basic meaning.
Frequently Asked Questions
Is appendices the plural of appendix?
Yes. Appendices is the traditional plural form of appendix and is widely used in formal English.
Is appendixes also correct?
Yes. Appendixes is also a correct plural form of appendix.
Which is better: appendices or appendixes?
Both are correct. Appendices is especially common in academic, scientific, and formal writing, while appendixes is also accepted.
What is the singular of appendices?
The singular form is appendix.
For example:
one appendix
two appendices
Can I use appendixes in a research paper?
Yes, unless your institution or style guide specifies appendices. In academic writing, however, appendices is generally the more conventional form.
Is “appendixs” correct?
No. Appendixs is not a standard English plural.
The correct forms are:
appendices
appendixes
Final Verdict: Appendixes or Appendices?
Both appendixes and appendices are correct plural forms of appendix.
The traditional and especially common form in formal writing is:
Appendices
The regular English plural is:
Appendixes
For a university thesis, dissertation, academic paper, scientific report, or formal professional document, appendices is often the more conventional choice.
However, appendixes is not a grammatical error.
The most important rule is to use one form consistently and follow any style guide that applies to your document.
Quick reminder:
Singular: Appendix
Plural: Appendices / Appendixes
Example:
The report includes three appendices containing additional research data.
or
The report includes three appendixes containing additional research data.
Both sentences are grammatically correct.
English Usage, Writing Tips, Academic Writing
