What’s the plural of “octopus”?
I saw several octopuses swimming in the tank.
The aquarium boasts a collection of magnificent octopi from around the world.
There were many octopus in the deep sea.
The scientist studied the behavior of two octopodeses.
What should be a simple question with an equally straightforward answer has become a matter of heated debate amongst grammarians and oceanographers! If you search the plural of octopus, you’ll get three possible answers: octopuses, octopi and octopodes.
Is it octopuses or octopi?
- Octopuses, octopi and octopodes are all correct ways to refer to more than one octopus.
- Octopus is the singular noun form.
There you have it: the noun and eight-limbed sea-creature, the octopus, accepts three different plural noun forms.
If you want to understand why “octopus” has three correct plurals, keep reading to learn about the history of the octopus.
The history of the word “octopus”
Octopi is the standard Latinized pluralization that other modern scientific names for creatures and organisms use. Think of other words like cactus, fungus, alumnus and hippopotamus all end in –us as a singular and switch to –i to denote a plural ending.
The thing about the word octopus is that it doesn’t originate from Latin. As it turns out, octopus comes from the Greek word oktōpous, meaning “eight-foot.” As etymonline states on the history of octopus, “the classically correct Greek plural (had the word been used in this sense in ancient Greek) would be octopodes.”
If the Greek pluralization were in use today, the plural would be octopodes. However, as it stands, this word rarely appears and probably sounds arcane to most modern ears.
We tend to follow suit with the sentiment that Etymonline shares: “it probably is best to let such words follow the grammar of the language that uses them, and octopuses probably works best in English.”
This leaves us with the regular English form, octopuses. Octopuses is much more common and widely used than octopi and octopodes, and it’s the plural form that most will recognize in conversation.
The majority of online dictionaries only recognize octopuses as the plural of octopus. As we like to say on this corner of the web, ‘what’s good sauce for the goose is good for the gander’, . . . or should we say octopus?
What are octopi?
The octopus, which are members of the Cephalopoda species, are a kind of mollusk and sea animal that have blue blood and tentacles.
Is octopus a regular or irregular plural noun?
The standard plural, octopuses, uses the regular plural form, which adds an -es.
Octopi is the original Latin plural, and uses the distinct Latin suffix, -i. Octopi are in good company, and they are not the only Latin (or near Latin) words to endure in Modern English.
| Singular | Plural |
|---|---|
| cactus | cacti (or cactuses) |
| octopus | octopi (or octopuses) |
| radius | radii (or radiuses) |
| fungus | fungi (or funguses) |
| alumnus | alumni (or alumnuses) |
| syllabus | syllabi (or syllabuses) |
Cactus, fungus, alumnus, hippopotamus, and so on all use the Latinate -i suffix, and have conserved their form since its inception (or near inception) as a word/noun.
Therefore, octopi is irregular as a plural noun; likewise, cacti, fungi, alumni, syllabi are all Latinate in plural form as well, and are, to that extent, irregular.
Examples of “octopus” in sentences
| Examples of “octopus” | Examples of “octopuses” |
|---|---|
| The thin skin of the octopus absorbs additional oxygen. | Octopuses live in every ocean, and different species have adapted to different marine habitats. |
| The Hawaiian day octopus (Octopus cyanea) lives on coral reefs; argonauts drift in pelagic waters. | Octopuses have three hearts; a systemic or main heart that circulates blood around the body and two branchial or gill hearts that pump it through each of the two gills. |
| The giant Pacific octopus (Enteroctopus dofleini) is often cited as the largest known octopus species. | Octopuses hide in dens, which are typically crevices in rocky outcrops or other hard structures, though some species burrow into sand or mud. |
| The mouth of an octopus, located underneath the arms, has a sharp hard beak. | Octopuses are not territorial but generally remain in a home range; they may leave in search of food. |
| Each of the eight arms senses and responds to light, allowing the octopus to control the limbs even if its head is obscured. | Octopuses mainly move about by relatively slow crawling with some swimming in a head-first position. |
Origin of the word octopus
The scientific Latin term octopus was derived from:
Ancient Greek ὀκτώπους, a compound form of ὀκτώ (oktō, “eight”) and πούς (pous, “foot”), itself a variant form of ὀκτάπους.
Worksheet: Irregular plurals
We saw several ______ swimming near the coral reef.
The aquarium added a new ______ to its exhibit.
Scientists studied the behavior of different ______ species.
The desert is home to many ______.
The forest was teeming with unusual ______.
FAQs
What plural forms exist for octopus?
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Which octopus plural is most common?
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Why are there three plural forms?
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Is octopodes commonly used?
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Is using “octopus” as plural wrong?
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Sources
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Wikipedia, octopus.
Yash, D. "How to Use Octopus Plural (Octopus, Octopuses, Octopi?)." Grammarflex, Aug 24, 2025, https://grammarflex.com/octopus-plural/.
