Appendices or Appendixes: Which Spelling Is Correct?

When you write formal documents or academic papers, you may wonder about the correct plural form of “appendix.” Should it be appendices or appendixes? Both are technically correct, but their use depends on context, regional preferences, and specific style guides, such as APA style. This article explains the difference, how to use each form, and why consistency in usage is key in professional and academic writing.

What Is There Confusion Appendices or Appendixes?

The confusion stems from the word appendix definition, which has two primary meanings: a section at the end of a book or document containing supplementary material, or a small organ in the human body. Depending on the context, the pluralization rules differ. For example, in medical contexts, the plural is often “appendixes,” while in academic writing, “appendices” is more common.

The plural forms are interchangeable, but many writers prefer one form over the other due to grammar rules or regional norms. This inconsistency causes issues, especially in formal writing. Choosing the correct plural depends on understanding the definition, context, and standard usage in your writing. For instance, APA format often requires “appendices” when referring to text at the end of a research paper.

Is the Appendices Word Correct?

Yes, the word “appendices” is correct. It is the classical plural form of “appendix,” following Latin grammar rules where nouns ending in “-ix” become “-ices” in the plural. “Appendices” is widely used in academic and formal writing to refer to supplementary materials, such as charts, graphs, or additional notes, included at the end of a document. It is also the preferred form in academic styles like APA, ensuring clarity and professionalism in scholarly contexts.

Definition

The term “appendices” refers to additional sections added to a document or book. It is the preferred spelling in formal and academic contexts.

Meaning

“Appendices” comes from the Latin word appendices, meaning “attachments.” It is widely accepted when referring to supplementary material like charts, graphs, or detailed information that enhances the main text. 

For instance, in a thesis, “appendices” provide extra details without cluttering the main body.

Usage

In professional writing, “appendices” is the correct plural when discussing sections that offer additional content at the end of a text.

For example: “The report includes three appendices, detailing our methodology, results, and supplementary data.”

Is the Appendixes Word Correct?

Yes, the word “appendixes” is correct. It follows modern English pluralization rules, adding “-es” to nouns ending in “-x.” While less common in academic writing, it is widely used in medical and scientific contexts to refer to the anatomical appendix. 

In academic contexts, “appendices” is typically preferred for supplementary materials. Both forms are valid, but their usage depends on the context and audience.

Definition

“Appendixes” is another correct plural form of “appendix.” However, it is more commonly used for the organ plural in biological or medical contexts.

Meaning

When discussing anatomy, “appendixes” refers to the plural of the appendage known as the appendix. It is less common in academic writing about documents or books.

Usage

“Appendixes” is widely used in informal contexts or when referring to physical or anatomical terms. 

For example: “The patient’s abdominal pain was linked to inflamed appendices.”

Quick Summary

Feature	Appendices	Appendixes
Usage	Academic writing, documents	Medical, anatomical contexts
Preferred Spelling	APA style, formal writing	Informal or biological terms
Examples	“Refer to the appendices.”	“The doctor examined the appendixes.”

Appendices or Appendixes as a Part of Speech

Both “appendices” and “appendixes” function as plural forms of “appendix.” They are nouns used to describe either a supplementary section in a document or the organ name. The choice depends on the context of usage and the need for consistency.

While both terms can coexist in English, ensuring the right word aligns with the meaning and intent of your content is critical. If you are writing a formal paper, choose “appendices.”

Pronunciation of Appendices or Appendixes

Both forms have distinct pronunciations. “Appendices” is pronounced as uh-pen-duh-seez, while “appendixes” is pronounced as uh-pen-diks-iz. Although similar, the slight difference reflects their context. 

Readers often associate “appendices” with formal writing and “appendixes” with biological terms.

Side-by-Side Comparison Appendices or Appendixes

Aspect	Appendices	Appendixes
Formality	More formal	Less formal
Academic Use	Preferred	Rare
Biological Context	Rare	Common

Which One Is More Acceptable Appendices or Appendixes?

In most professional settings, “appendices” is the preferred spelling due to its wide acceptance in academic writing and style guides like APA. While “appendixes” is correct, its use is largely limited to medical or casual discussions.

However, in any writing, maintaining consistent spelling is crucial. Choose one form and stick to it throughout your document.

Appendices in British English and American English

In British English, “appendices” is widely used in both academic and general contexts, reflecting traditional Latin pluralization rules. This classical form dominates due to its formal tone and alignment with established conventions.

In American English, “appendices” is also preferred in academic and professional writing, particularly when referring to supplementary materials. However, “appendixes” appears more frequently in informal contexts or when discussing biological topics, such as the anatomical appendix. While both forms are correct, understanding the audience and context helps ensure appropriate usage.

Appendixes in British English and American English

In British English, “appendixes” is rarely used and typically appears in informal or casual contexts. The preferred term for formal and academic use is “appendices.” 

In American English, “appendixes” is slightly more common but still less favored than “appendices.” This preference highlights the subtle regional differences in the standard usage of the term.

Common Mistakes and How to Avoid Them

One common mistake writers make is using both “appendices” and “appendixes” interchangeably in the same document. This inconsistency can confuse readers and disrupt the clarity of your writing. 

To avoid this, always choose one form and stick to it throughout your text. Refer to the specific style guide you’re following, such as APA format, to ensure your choice aligns with the required standards.

Trick to Remember the Difference Between Appendices and Appendixes

An easy way to differentiate between the two is by linking “appendices” with academic or literary contexts, where it is the most widely accepted plural form. On the other hand, associate “appendixes” with anatomical or medical discussions, where it refers to the plural of the human appendix. 

If you’re writing about additional sections in a book, report, or paper, “appendices” is the safest and most consistent spelling to use.

Origins of Appendices and Appendixes

Appendices

The word “appendices” has its roots in Latin, originating from the term appendix. In Latin, nouns ending in “-ix” form their plural by replacing the suffix with “-ices.” This classical linguistic origin explains why “appendices” is the preferred form in formal and academic writing. It carries a sense of tradition and sophistication, making it the dominant choice for referring to supplementary materials like charts, graphs, or notes in scholarly documents. Academic styles, such as APA, also endorse “appendices” for consistency in professional contexts.

Appendixes

In contrast, “appendixes” follows modern English pluralization rules. These rules typically add “-es” to singular nouns ending in “-x,” reflecting the natural evolution of the English language. While grammatically correct, “appendixes” is less common in academic or literary circles. However, it is widely used in medical and scientific contexts, where it refers to the anatomical structure of the appendix.

Synonyms of Appendices or Appendixes

Appendices

• Addenda
• Attachments
• Supplements
• Annexes
• Postscripts
• Endnotes
• Additions
• Updates
• Notes
• Extra material

Appendixes

• Tables
• Charts
• Sections
• Catalogs
• Listings
• Indices
• Exhibits
• Attachments
• Entries
• Annexes

Sentences in Daily Usage of Appendices or Appendixes

Appendices

• The report’s appendices contained supplemental data tables.
• Scholars referred to the appendices for historical references.
• The appendices provided in-depth explanations for complex theories.
• Appendices in legal documents often include terms and conditions.
• The author’s appendices were essential for understanding the methodology.
• Appendices in textbooks often summarize additional resources.
• Detailed maps in the appendices helped clarify the expedition route.
• Scientific papers often rely on appendices to present raw data.
• Without the appendices, readers might struggle to follow the arguments.
• The appendices expanded on the statistical analysis in the main text.

Appendixes

• Surgeons studied the structure of human appendixes in medical school.
• The lab conducted experiments on animal appendixes.
• Pathologists examined diseased appendixes for abnormalities.
• The hospital performed research on inflamed appendixes.
• Specimens of removed appendixes were preserved for future studies.
• Anatomy books include diagrams of healthy and infected appendixes.
• Doctors analyzed samples from several appendixes for their study.
• Appendixes, though small, play a role in gut immunity.
• The museum displayed ancient mummified appendixes.
• Researchers debated the evolutionary purpose of appendixes in mammals.

FAQs

Are both “appendices” and “appendixes” correct?

Yes, both are correct, but “appendices” is used in academic contexts, while “appendixes” is preferred in medical or scientific settings.

Which form follows APA style?

APA style uses “appendices” for supplementary material.

How to ensure consistency?

Pick one form (preferably “appendices” in academic writing) and stick to it throughout.

What is the plural of the human appendix?

The plural is “appendixes” in medical contexts.

When to use “appendices” in academic writing?

Use “appendices” for supplementary materials like charts, graphs, or additional notes in formal documents.

Conclusion

Understanding the difference between “appendices” and “appendixes” is key to polished, professional writing. Both are correct plural forms of “appendix,” but their usage depends on context. “Appendices” is commonly used in academic writing to refer to supplementary materials, such as charts, graphs, or additional notes, included at the end of a document.

On the other hand, “appendixes” is typically used in medical or scientific contexts, referring to the anatomical structure. For academic work, APA style specifically prefers “appendices.” To maintain clarity and professionalism, choose the appropriate term based on context and use it consistently throughout your document. This attention to detail ensures your writing is not only effective but also adheres to accepted conventions.