You are not alone if you have ever stopped while writing and wondered: “Is it addendums or addenda?” This question appears in offices, legal documents, academic papers, contracts, emails, and reports every single day.
People search for addendums or addenda because both forms look correct, both are widely used, and both even appear in professional writing. That makes the confusion real and persistent.
The problem comes from English borrowing words from Latin. English loves to keep some Latin plural forms while also creating its own English style plurals. As a result, writers are left unsure which version sounds right, looks professional, or fits their audience.
A lawyer may prefer one form. A business email may prefer another. A student may be marked wrong for choosing the wrong one.
This article clears all that confusion in one place. You will get a quick answer, understand the origin of the words, learn British and American usage, avoid common mistakes, and get clear advice on which spelling you should use. By the end, addendums or addenda will no longer slow you down.
Addendums or Addenda – Quick Answer
Both addendums and addenda are correct plural forms of addendum.
However, they are used in different contexts.
- Addenda is the original Latin plural.
- Addendums is the modern English plural.
Simple rule:
- Use addenda in formal, academic, or legal writing.
- Use addendums in everyday business or general English.
Examples:
- ✅ The report includes two addenda. (formal)
- ✅ The contract has three addendums attached. (business English)
Both are grammatically correct.
The Origin of Addendums or Addenda
To understand this confusion, we need to go back to Latin.
Latin origin
- Addendum comes from Latin addere, meaning “to add.”
- In Latin:
- Singular: addendum
- Plural: addenda
So originally:
- One addition = addendum
- Multiple additions = addenda
What happened in English?
English borrowed the word addendum but slowly applied its own plural rules. English usually forms plurals by adding -s or -es, not by changing word endings.
That is how addendums appeared.
Over time:
- Addenda stayed popular in formal fields.
- Addendums became common in everyday use.
This pattern happens with many Latin words:
- curriculum → curricula / curriculums
- forum → fora / forums
- memorandum → memoranda / memorandums
English accepts both, depending on context.
British English vs American English Spelling
Both British and American English accept addendums and addenda, but usage preference differs slightly.
American English
- Addendums is more common in:
- Business writing
- Corporate contracts
- Emails
- Addenda is still used in:
- Legal documents
- Academic texts
British English
- Addenda is more common overall.
- Addendums is accepted but sounds more informal.
Comparison Table
| Form | British English | American English | Tone |
|---|---|---|---|
| addenda | Very common | Common | Formal |
| addendums | Acceptable | Very common | Informal / Business |
Neither form is wrong. The difference is tone, not correctness.
Which Spelling Should You Use?
The best choice depends on your audience and purpose.
Use addenda if:
- You are writing a legal document
- You are writing an academic paper
- You want a formal tone
- Your audience expects traditional grammar
Example:
“The policy changes are listed in the addenda.”
Use addendums if:
- You are writing emails
- You are creating business contracts
- You want clarity for general readers
- You are writing online content
Example:
“Please review the addendums before signing.”
Global advice
If your audience is international or non-native:
- Addendums is easier to understand
- It follows normal English plural rules
Common Mistakes with Addendums or Addenda
Even experienced writers make mistakes with these words.
1. Mixing singular and plural
- ❌ These addendum are attached.
- ✅ These addenda are attached.
- ✅ These addendums are attached.
2. Using “addenda” as singular
- ❌ An addenda was included.
- ✅ An addendum was included.
3. Thinking one form is wrong
Both forms are correct. The mistake is believing one is “bad English.”
4. Inconsistent usage
Do not mix forms in the same document.
- ❌ addenda on page one, addendums on page two
- ✅ choose one and stay consistent
Addendums or Addenda in Everyday Examples
Emails
- “Please find the addendums attached to the agreement.”
- “The updated terms are included as addenda.”
News
- “The bill passed with several addenda added later.”
Social Media
- “Oops! Added a few addendums to the post.”
Formal Writing
- “Supporting data can be found in the addenda section.”
Legal Writing
- “This contract includes two addenda.”
Addendums or Addenda – Google Trends & Usage Data
Search data shows:
- Addendums is searched more often by:
- Business users
- General writers
- ESL learners
- Addenda is searched mostly by:
- Students
- Lawyers
- Academics
By region:
- United States: addendums slightly more popular
- United Kingdom: addenda preferred
- Global searches: addendums rising faster
This shows a clear trend. English is slowly favoring English-style plurals, but traditional forms remain strong in formal fields.
Comparison Table: Addendums vs Addenda
| Feature | Addendums | Addenda |
|---|---|---|
| Grammar | English plural | Latin plural |
| Tone | Informal / Business | Formal / Academic |
| Accepted | Yes | Yes |
| Common in US | Very common | Common |
| Common in UK | Less common | Very common |
| ESL friendly | Yes | Less |
FAQs – Addendums or Addenda
1. Are addendums and addenda both correct?
Yes. Both are grammatically correct plurals of addendum.
2. Which one should I use in a contract?
Most legal documents prefer addenda.
3. Can I use addendums in academic writing?
It is better to use addenda in academic work.
4. Is addenda plural or singular?
Addenda is plural. Singular is addendum.
5. Is addendums American English?
It is more common in American English, but accepted everywhere.
6. Should I avoid addendums?
No. It is correct and widely used.
7. Can I mix addenda and addendums?
No. Choose one form and be consistent.
Conclusion
The confusion between addendums or addenda comes from English borrowing Latin words and then applying its own rules. The good news is simple: both forms are correct. The difference is not about right or wrong, but about style, tone, and audience.
If you want to sound formal, traditional, or academic, choose addenda. If you want clarity, simplicity, and modern usage, choose addendums.
Business writing often prefers addendums. Legal and academic writing often prefers addenda. Neither choice will harm your credibility if used in the right context.
The most important rule is consistency. Pick one form and use it throughout your document. Doing this shows professionalism, confidence, and language control.
Now that you understand the origin, usage, and differences, you can use addendums or addenda correctly every time without hesitation.
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My name is James Whitmore.I am a language research writer. I explore the history and evolution of English words. I write detailed comparisons explaining why spellings change over time and how British and American English diverged. My articles add depth and credibility to grammar comparison topics.
