When I first came across Octopuses or Octopi, I understood why this spelling confuses so many people both look like they should be correct. If you’ve ever paused while writing and wondered which plural sounds natural and grammatically accurate, you’re in the right place. I’ll break down the difference simply, so you can use the right word with confidence.
Which is correct: octopuses or octopi?
Octopuses is the standard plural in modern English, while octopi is a common but less preferred form.
Quick Answer
Both octopuses and octopi are used as plural forms of octopus, so it is not accurate to say that one is simply “wrong.” However, octopuses is the safest and most straightforward choice in modern English, especially in formal writing.
Octopi is also established and widely recognized, although it comes from an incorrect assumption that octopus was a Latin word requiring a Latin -i plural.
If you are writing an essay, article, email, report, or school assignment and want the least controversial option, use octopuses.
Quick Comparison Table
| Word/Form | Main Use | Example |
| octopus | Singular form | I saw one octopus at the aquarium. |
| octopuses | Standard English plural | Several octopuses were swimming near the reef. |
| octopi | Established alternative plural | The researchers observed several octopi. |
| octopodes | Rare Greek-based plural | The scientific text mentioned several octopodes. |
Oxford Learner’s Dictionaries gives octopuses as the plural, while Cambridge lists octopuses or octopi in its American English entry. Merriam-Webster also recognizes octopuses and octopi, with octopodes as another, much less common form.
What Does “Octopuses” Mean?
Octopuses is the plural of octopus. It means more than one of these eight-armed marine animals.
For example:
- We saw three octopuses at the aquarium.
- The documentary followed several octopuses in the Pacific Ocean.
- Young octopuses can change color to blend into their surroundings.
The word octopus refers to a sea creature with a soft body and eight arms. Although people often call these appendages “tentacles,” zoological descriptions commonly distinguish the arms of an octopus from true tentacles.
For ordinary English writing, octopuses works just like many other English plurals: add -es to the singular noun.
one octopus → two octopuses
This makes it easy to use in everyday conversation, schoolwork, journalism, and general writing.
What Does “Octopi” Mean?
Octopi is another plural form of octopus. It is widely recognized and has a long history in English, so calling it meaningless or simply a spelling error would be misleading. Merriam-Webster lists octopi as a plural of octopus, and Cambridge also recognizes it.
For example:
- The aquarium houses several octopi.
- Scientists studied how the octopi responded to changes in light.
- We watched two octopi move across the seafloor.
The interesting part is its history. The ending -i was adopted because octopus looks like a Latin noun ending in -us. People therefore treated it as though its plural should follow a Latin pattern.
But octopus ultimately comes from Greek, not Classical Latin. Its Greek roots relate to “eight” and “foot.”
That is why the history of octopi is more complicated than simply saying, “The Latin plural is correct.”
Octopuses vs Octopi: Key Difference
The main difference is not meaning.
Both octopuses and octopi can refer to more than one octopus.
The difference is mainly in how the plural was formed:
- octopuses uses the normal English plural ending -es.
- octopi was created under the assumption that octopus should receive a Latin-style -i ending.
So these sentences have essentially the same meaning:
The divers saw several octopuses near the rocks.
The divers saw several octopi near the rocks.
If you want the simplest modern English choice, octopuses is usually preferable.
When Should You Use Octopuses?
In Everyday Conversation
Use octopuses when you are simply talking about more than one octopus.
We saw two octopuses while snorkeling.
It sounds natural and follows an ordinary English plural pattern.
In School or Academic Writing
Octopuses is an excellent choice for essays, reports, research summaries, and educational writing.
The researchers examined how octopuses respond to changes in temperature.
It avoids the unnecessary question of whether the reader accepts the traditional -i form.
In Formal Writing
When clarity and conventional modern usage matter, octopuses is a strong choice.
Several octopuses were observed during the survey.
You do not need to use octopi simply to make the writing sound more scientific.
In News, Articles, and General Publications
Octopuses is also appropriate for general-audience writing.
The rescue team discovered several octopuses trapped in a shallow pool.
The form is immediately understandable and grammatically straightforward.
When Should You Use Octopi?
When It Fits the Style or Audience
Because octopi is an established plural, you may encounter and use it in informal, general, or stylistically traditional writing.
The aquarium’s newest exhibit features five giant octopi.
There is no need to treat the word as if it were an obvious spelling mistake.
When Quoting or Preserving Someone’s Wording
If you are quoting an original source that uses octopi, you should not silently change the word merely because you personally prefer octopuses.
When the Familiar Form Is Expected
Some readers are very familiar with octopi, and the word remains common enough that it is readily understood.
Still, if you are choosing the plural yourself, octopuses is the safer general-purpose option.
Is It “Octopuses” or “Octopi” in a Sentence?
Both can be grammatically used as plurals.
“I saw several octopuses.”
Correct.
Here, octopuses is the plural subject or object referring to multiple animals.
“I saw several octopi.”
Also accepted in dictionaries that recognize octopi as a plural.
The important point is that the plural noun must agree with the rest of the sentence.
Several octopuses are hiding under the rocks.
Not:
❌ Several octopuses is hiding under the rocks.
Because octopuses is plural, use the plural verb are.
Octopus or Octopuses?
Use octopus when you mean one.
Use octopuses when you mean more than one.
Singular: The octopus is hiding.
Plural: The octopuses are hiding.
This is the most useful rule for everyday writing.
The same distinction applies if you choose octopi:
One octopus was swimming near the boat.
Several octopi were swimming near the boat.
Octopus or Octopi for More Than One?
If you are referring to multiple animals, you need a plural form.
One animal
I photographed an octopus.
More than one animal
I photographed several octopuses.
You can also write:
I photographed several octopi.
However, octopus by itself should not normally be used as the countable plural when you are specifically counting individual animals.
Octopuses or Octopi in Formal Writing?
For most formal writing, octopuses is the better default.
That does not mean octopi suddenly becomes ungrammatical in every formal context. Rather, octopuses is more transparent because it follows ordinary English plural formation and avoids the historical confusion surrounding octopi.
Oxford Learner’s Dictionaries lists octopuses as the plural, while Merriam-Webster recognizes both forms.
If you are unsure which one your teacher, editor, or workplace prefers, octopuses is the uncomplicated choice.
Common Phrases With Octopuses
Octopuses in the Ocean
This phrase refers to octopuses living in their natural marine environment.
The documentary showed octopuses hunting on the ocean floor.
Giant Pacific Octopuses
This refers to multiple giant Pacific octopuses.
Giant Pacific octopuses can be impressive animals to observe.
Octopuses at the Aquarium
A natural phrase for multiple animals kept or displayed at an aquarium.
The children were fascinated by the octopuses at the aquarium.
Octopus Species
When discussing different kinds of octopus, species can itself remain unchanged in the plural.
Scientists have identified many octopus species.
This is different from deciding whether the plural of octopus should be octopuses or octopi.
Common Mistakes
1. Treating Octopi as the Only Correct Form
❌ Octopi is the only correct plural.
✅ Octopuses and octopi are both recognized plural forms.
The idea that octopi is automatically the only correct answer is too simplistic.
2. Calling Octopuses Incorrect
❌ Octopuses is wrong because octopus ends in -us.
✅ Octopuses is a standard English plural.
English nouns do not all follow one universal rule based on their final letters.
3. Using a Singular Verb With Octopuses
❌ Several octopuses is hiding nearby.
✅ Several octopuses are hiding nearby.
The plural noun requires a plural verb.
4. Writing “Octopusses”
❌ The aquarium has four octopusses.
✅ The aquarium has four octopuses.
The standard spelling is octopuses, with one s after pu.
5. Assuming Every -US Word Takes -I
❌ Every English noun ending in -us must become -i in the plural.
✅ English plural formation depends on the individual word and its history and usage.
For example, English has words such as bus → buses, so the ending -us does not automatically determine the plural.
6. Using Octopodes in Ordinary Writing Without Knowing What It Is
❌ I saw three octopodes at the local aquarium.
This is not necessarily grammatically impossible, but octopodes is rare and can sound highly specialized or unusual.
✅ I saw three octopuses at the local aquarium.
Merriam-Webster recognizes octopodes, but identifies it as a much less common plural.
Why Do People Get Octopuses and Octopi Wrong?
The confusion comes largely from the appearance and history of the word.
Octopus looks like many Latin-derived nouns ending in -us, so it is easy to assume that the plural should end in -i.
That assumption produced octopi.
The problem is that the word ultimately traces back to Greek. Its Greek origin led some people to favor the Greek-derived plural octopodes instead. Meanwhile, English speakers also naturally formed the regular English plural octopuses.
So English ended up with several competing plural forms.
This is a good example of why English plurals cannot always be predicted simply by looking at the last two or three letters of a noun.
Can Both Forms Be Correct?
Yes.
Octopuses and octopi are both recognized plural forms in major English dictionaries. Cambridge lists both, and Merriam-Webster does as well.
However, there is an important practical distinction:
- Octopuses is the straightforward English plural.
- Octopi is an established alternative with a historically Latin-looking formation.
- Octopodes is another historical form, based on Greek, but it is rare.
So if someone writes octopi, you should not automatically mark it as a spelling error. But if you are choosing the form for your own writing and want maximum simplicity, octopuses is usually the best choice.
British vs American English
There is no simple British-versus-American rule that says one variety must use octopuses and the other must use octopi.
Both forms occur in English, and major dictionaries recognize the variation. Cambridge’s American English entry explicitly gives octopuses or octopi.
Oxford Learner’s Dictionaries, meanwhile, gives octopuses as the plural in its main entry.
Therefore, it is better not to memorize this as a strict US-versus-UK spelling difference.
Pronunciation
The singular octopus is commonly pronounced approximately as:
OK-tuh-pus
The plural octopuses is pronounced approximately:
OK-tuh-pus-iz
The -es ending adds an extra syllable.
Octopi is commonly pronounced approximately:
OK-tuh-pie
Cambridge gives the American pronunciation of octopi with the final sound represented as /paɪ/.
The pronunciation difference can make octopi sound quite distinctive in conversation, while octopuses makes the English plural ending obvious.
Word Origin and History
The history of octopus explains much of the plural confusion.
The word ultimately comes from Greek, from elements meaning eight and foot. It entered English in the eighteenth century.
When the word became established in English, speakers and writers formed different plurals.
Octopuses developed by applying an ordinary English plural ending.
Octopi developed from the assumption that octopus was a Latin noun that should take a Latin-style plural ending.
Later, octopodes appeared based on the Greek plural pattern. Merriam-Webster describes these three forms and explains the different reasoning behind them.
So the debate is not really about one spelling mistake. It is the result of English adopting a word with a complicated linguistic history and then treating it in several different ways.
Simple Memory Trick
Remember this:
One octopus, many octopuses.
If you want the easiest everyday English rule, simply add -es:
octopus → octopuses
You can remember octopi as an accepted alternative rather than feeling that you must use it.
Quick Decision Guide
Are you talking about one animal?
→ Use octopus.
Are you talking about several animals?
→ Use octopuses.
Have you seen the word octopi?
→ It is also an established plural form.
Are you writing a school assignment, article, or formal report?
→ Octopuses is the safest straightforward choice.
Are you wondering whether octopi is automatically wrong?
→ No. Major dictionaries recognize it as a plural of octopus.
Have you encountered octopodes?
→ It is a rare alternative plural, not the usual choice for everyday English.
Mini Quiz
1. Which sentence uses the most straightforward plural form?
A. The divers saw five octopuses.
B. The divers saw five octopus.
Answer: A — octopuses
Octopuses is the regular English plural used for more than one octopus.
2. Which sentence is correct?
A. One octopuses was hiding under a rock.
B. One octopus was hiding under a rock.
Answer: B — octopus
The singular form is octopus.
3. Which sentence correctly uses a plural verb?
A. Several octopuses are moving toward the reef.
B. Several octopuses is moving toward the reef.
Answer: A — are
The plural subject octopuses takes are.
4. Is “octopi” a recognized plural?
A. Yes
B. No
Answer: A — Yes
Major dictionaries such as Cambridge and Merriam-Webster recognize octopi as a plural form.
5. Which spelling is the standard English plural?
A. octopusses
B. octopuses
Answer: B — octopuses
The standard spelling is octopuses.
6. Which form is the easiest choice for general formal writing?
A. octopuses
B. octopodes
Answer: A — octopuses
Octopuses is clear, familiar, and straightforward, whereas octopodes is rare.
7. What does “octopi” refer to?
A. One octopus
B. More than one octopus
Answer: B — More than one octopus
Octopi is an established alternative plural of octopus.
FAQs
Is octopuses or octopi correct?
Both octopuses and octopi are recognized plural forms. However, octopuses is the simpler choice and is especially useful when you want conventional English plural formation.
Is octopi grammatically correct?
Yes, octopi is recognized as a plural form by major dictionaries. Its formation comes from treating octopus as though it were a Latin noun with a Latin-style plural, even though the word ultimately comes from Greek.
Is octopuses the preferred plural?
For many modern English contexts, octopuses is the safest and most straightforward choice. Oxford Learner’s Dictionaries lists octopuses as the plural, while other dictionaries recognize both forms.
Why is the plural octopi if octopus is Greek?
It is not actually because octopi is the true Greek plural. The -i ending arose from the assumption that octopus was a Latin noun requiring a Latin-style plural. The word ultimately has Greek roots, which is why octopodes was also proposed.
Is octopuses grammatically wrong?
No. Octopuses is a valid and widely recognized English plural. It is formed using the normal English plural ending -es.
What is the plural of octopus in American English?
American English uses both octopuses and octopi. Cambridge’s American English dictionary specifically lists both forms.
What is the plural of octopus in British English?
Octopuses is a standard British English plural, and octopi is also encountered. It is therefore better not to treat the choice as a strict British-versus-American difference.
Is octopodes a correct word?
Yes, octopodes is a recognized but rare plural form. It was formed from the Greek plural pattern associated with the word’s ultimate origin. It is much less common than octopuses or octopi.
Should I use octopuses in an academic paper?
Usually, yes. Octopuses is a clear and conventional choice for general academic writing. If a particular journal, institution, or scientific taxonomy uses another form, follow that publication’s style requirements.
Is “two octopuses” correct?
Yes. Two octopuses is completely correct.
We saw two octopuses near the coral reef.
Can I say “two octopi”?
Yes. Two octopi is also a recognized construction because octopi is an established plural form. However, two octopuses is the simpler choice if you want to avoid the historical controversy surrounding the -i ending.
Final Takeaway
The easiest rule is:
One octopus, two octopuses.
Octopuses is the straightforward English plural and the best default for most writing. Octopi is also an established and widely recognized plural, so it is not accurate to call it simply “wrong.” A third form, octopodes, exists as a rare Greek-based plural but is uncommon in everyday English.
When in doubt, choose octopuses.
My name is Michael Turner, and I have always been fascinated by animals and the unique relationships people build with them. I enjoy researching naming ideas from different cultures, languages, and traditions to help pet owners discover names that truly stand out. At Meanixo, I write informative articles designed to make pet naming fun, simple, and stress-free. I believe reliable information and creativity should always go hand in hand.
Books:
- The Ultimate Pet Name Collection
- Living Better with Pets
Daniel Brooks
Sophia Mitchell