Octopuses or Octopi: Which Is Correct?

Octopuses or octopi? Both are accepted plural forms of octopus, but octopuses is the clearest choice for most modern English writing.

The word octopuses follows the regular English plural rule, while octopi follows a Latin-style pattern that people have applied to the word.

The debate comes from the history of the word octopus. Although it ends in -us, it ultimately comes from Greek rather than being an ordinary Latin noun of the type that forms plurals in -i.

That is why some people question octopi, even though major dictionaries recognize it as an established plural.

So, which form should you use in a school assignment, blog post, or everyday conversation?

In this guide, we will compare octopuses and octopi, explain the word’s origin, look at the rare alternative octopodes, and give you examples to make the choice easy.

Octopuses or Octopi: Quick Answer
What Does Octopus Mean?
Octopuses vs Octopi: Key Differences
Why Is Octopuses the Preferred Form?
Why Do People Say Octopi?
Is Octopodes Also Correct?
Octopuses or Octopi in Sentences
Common Mistakes to Avoid
How to Remember the Correct Plural
Frequently Asked Questions
Conclusion and Key Takeaways

1. Octopuses or Octopi: Quick Answer

Both octopuses and octopi are accepted English plurals of octopus. However, octopuses is the standard, regular English plural and the best choice for most general and formal writing. Octopi is also widely recognized, although its Latin-style ending does not match the word’s ultimate Greek origin. Cambridge Dictionary lists both forms, while Oxford Advanced Learner’s Dictionary lists octopuses.

Quick Rule: Use octopuses as your default plural. You can also use octopi, but do not assume it is the only correct form.

2. What Does Octopus Mean?

An octopus is a sea animal with a soft body and eight arms covered with suckers. It belongs to a group of marine animals called cephalopods.

The word can refer to one animal or, in some contexts, the animal’s flesh when used as food.

Examples:

We saw an octopus near the rocks.
The aquarium has an octopus in its largest tank.
An octopus can move through narrow spaces.
The restaurant serves grilled octopus.

When you talk about more than one of these animals, you need a plural noun.

For example:

We saw three octopuses near the reef.
The aquarium has several octopi.
Scientists studied a group of octopuses.

Both plural forms communicate the same basic meaning. The difference is how the plural is formed, not what the animals are.

For a dictionary definition, see the Cambridge Dictionary entry for octopus.

3. Octopuses vs Octopi: Key Differences

Feature	Octopuses	Octopi
Singular form	Octopus	Octopus
Plural form	Octopuses	Octopi
Status	Accepted and standard	Accepted by major dictionaries
Formation	Regular English plural	Latin-style plural pattern
Frequency	Most common and generally preferred	Also used, but less preferred as a default
Best use	General, academic, and everyday writing	When this established alternative suits the context
Example	Two octopuses swam past us.	Two octopi swam past us.

The important point is that octopuses is not a less intelligent or less formal choice. It is the normal English plural and works well in virtually any context.

Similarly, octopi is not automatically a spelling mistake. Cambridge and Merriam-Webster recognize it as a plural of octopus. Dictionary.com also explains that both forms are acceptable. Cambridge Dictionary · Dictionary.com

Which one should you use?

Choose octopuses if you want the most straightforward form for an article, school assignment, report, or general conversation.

Choose octopi if you prefer the established alternative and your context allows it.

If you are following a particular dictionary, publication, or style guide, use its preferred form consistently.

4. Why Is Octopuses the Preferred Form?

The word octopuses follows a common English plural pattern: add -s or -es to a singular noun.

For example:

book → books
dish → dishes
box → boxes
octopus → octopuses

This pattern is familiar to English learners, so octopuses is easy to understand and use.

Oxford Advanced Learner’s Dictionary lists octopuses as the plural of octopus. Merriam-Webster also identifies octopuses as the most common plural form. These references make it a reliable choice for modern writing.

Examples of the regular plural

Several octopuses live in the aquarium.
The divers photographed two octopuses.
Researchers observed octopuses in their natural habitat.
The documentary showed how octopuses hunt for food.
We learned about octopuses during our marine biology lesson.

Each sentence uses the same straightforward plural form.

Does octopuses sound less formal?

No. Octopuses is suitable for formal writing, scientific explanations, educational articles, news reports, and everyday conversation.

You do not need to replace it with octopi to sound educated. The regular English plural is a natural and correct choice.

5. Why Do People Say Octopi?

People use octopi because many English words ending in -us have Latin-style plurals ending in -i.

Examples include:

alumnus → alumni
stimulus → stimuli
radius → radii

By analogy, some speakers form octopus into octopi. The form has a long history in English and is recognized by major dictionaries.

However, the origin of octopus makes the comparison more complicated.

The word ultimately comes from the Greek oktōpous, referring to an eight-footed creature. It entered English through a Latinized scientific form, but that does not mean it follows the same Latin plural pattern as alumnus or stimulus.

That is why some language experts object to octopi on historical grounds. They argue that the regular English plural, octopuses, avoids applying a Latin rule to a word of Greek origin.

Still, language usage is not determined by word origins alone. Because octopi has become established in English, major dictionaries recognize it as a plural.

Expert Tip: Do not assume every English word ending in -us must change to -i in the plural. Check the word’s accepted plural forms instead.

6. Is Octopodes Also Correct?

Yes. Octopodes is a documented but rare plural of octopus. It follows the word’s Greek origin rather than the regular English pattern or the Latin-style ending.

The three forms are:

Octopuses: the regular English plural and the best everyday choice.
Octopi: an established alternative recognized by major dictionaries.
Octopodes: a rare Greek-derived alternative.

The word’s Greek background explains why octopodes exists. However, most English speakers are much more familiar with octopuses and octopi.

You may see octopodes in discussions about etymology, language history, or the different plurals of octopus. It is rarely necessary in ordinary writing.

For more on the historical debate, read Dictionary.com’s explanation of octopuses, octopi, and octopodes.

Should you use octopodes in your article?

Usually, no. Unless you are discussing Greek word origins or unusual plural forms, octopuses is clearer for most readers.

The goal of good writing is not to choose the most complicated word. It is to communicate accurately and naturally.

7. Octopuses or Octopi in Sentences

Examples can help you see how both plurals work in real writing.

Examples using octopuses

We saw several octopuses at the aquarium.
The divers photographed two octopuses near the seabed.
Octopuses use their arms to explore their surroundings.
The science teacher showed us pictures of octopuses.
Researchers observed octopuses during the study.
Three octopuses were resting beneath the rocks.
The documentary explained how octopuses find food.
Children watched the octopuses swim through the tank.
Some octopuses can change their appearance to blend into their surroundings.
The marine biology book contains a chapter about octopuses.

These sentences use the regular English plural and are appropriate for general and formal writing.

Examples using octopi

We saw several octopi at the aquarium.
The students read about octopi in science class.
The documentary featured octopi living near coral reefs.
Researchers discussed the behavior of octopi.
The aquarium’s guide included information about octopi.

These examples are also understandable and use an established plural form.

Can you replace octopi with octopuses?

In these examples, yes. The two forms refer to more than one octopus and generally mean the same thing.

For most readers, changing octopi to octopuses will make the sentence more straightforward without changing its meaning.

8. Common Mistakes to Avoid

Mistake 1: Saying octopi is always wrong

It is too strong to say that octopi is always incorrect. Although some usage guides prefer octopuses, Cambridge and Merriam-Webster recognize octopi as an accepted plural.

Better approach: Use octopuses as your default, but recognize that octopi exists in standard usage.

Mistake 2: Assuming octopus must follow the Latin rule

The ending -us does not automatically mean that a noun should form its plural with -i.

For example, English uses different plural patterns for words with different origins and histories. The accepted plural of a word must be checked individually when it is uncertain.

Mistake 3: Using octopuses as a singular noun

Incorrect: “I saw three octopuses, and one octopuses was hiding.”

Correct: “I saw three octopuses, and one octopus was hiding.”

Use octopus for one animal and octopuses or octopi for more than one.

Mistake 4: Treating octopodes as the everyday plural

Octopodes is a real form, but it is rare. Most readers will be more familiar with octopuses and octopi.

Mistake 5: Thinking the longest or oldest-looking form is always better

A word that looks more classical is not necessarily more suitable for modern English. Choose the form that is accurate, clear, and appropriate for your audience.

9. How to Remember the Correct Plural

Use this simple memory trick:

One octopus, two octopuses.

Think of the regular English pattern used in words such as bus → buses and dish → dishes. The plural octopuses is straightforward and easy to remember.

You can also keep this mini-guide in mind:

For everyday writing: octopuses
For an accepted alternative: octopi
For a rare Greek-derived form: octopodes

Quick practice quiz

1. Which is the best default plural for a general English article?

A. Octopuses

B. Octopuss

C. Octopusi

Answer: A. Octopuses.

2. Is octopi an accepted plural?

A. Yes

B. No

Answer: A. Yes. Major dictionaries recognize octopi as a plural of octopus.

3. Which plural is rare and based on the word’s Greek origin?

A. Octopuses

B. Octopodes

C. Octopuss

Answer: B. Octopodes.

4. Which sentence is correct?

A. We saw three octopus.

B. We saw three octopuses.

Answer: B. “We saw three octopuses.”

10. FAQs

Is it octopuses or octopi?

Both are accepted plurals of octopus. However, octopuses is the standard regular English plural and is the best choice for most writing.

Is octopi grammatically correct?

Yes. Octopi is recognized as a plural of octopus by major dictionaries, including Cambridge and Merriam-Webster. Some usage experts prefer octopuses because it follows the regular English plural rule.

What is the correct plural of octopus according to Oxford?

The Oxford Advanced Learner’s Dictionary lists octopuses as the plural of octopus. Other major dictionaries also recognize octopi.

Why is octopi sometimes considered incorrect?

The objection comes from the word’s Greek origin. Some writers argue that the Latin-style -i ending incorrectly treats octopus as a Latin noun that follows that plural pattern. However, octopi is established in English and is recognized by major dictionaries.

Is octopodes a real word?

Yes. Octopodes is a rare plural based on the Greek origin of octopus. It is much less common than octopuses and octopi.

Which form is best for formal writing?

Use octopuses as your default. It is clear, standard, and appropriate for academic writing, professional documents, and educational content.

Is octopuses more common than octopi?

Yes. Merriam-Webster identifies octopuses as the most common plural form. Both forms are understood, but octopuses is the safer default.

Can I use octopi in a school assignment?

Yes, unless your teacher or style guide specifies a particular form. To keep the wording straightforward, octopuses is generally the better choice.

Is octopuses an irregular plural?

No. Octopuses follows a regular English plural pattern by adding -es. The alternative octopi follows a different, Latin-style pattern.

What is the singular of octopuses?

The singular is octopus. For example, “One octopus was swimming near the rocks,” while “Two octopuses were swimming near the rocks.”

Conclusion

Both octopuses and octopi are accepted plural forms of octopus. However, octopuses is the best default for most modern English writing because it follows the regular English plural rule and is the most common form.

The alternative octopi has a long history and is recognized by major dictionaries, even though the word ultimately comes from Greek. A third form, octopodes, also exists but is rare.

When in doubt, write octopuses. It is clear, natural, and suitable for everyday conversation, educational articles, and formal writing.