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 was 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.
Remember that while all three plurals (octopuses, octopi, octopodes) are technically correct, “octopuses” is generally preferred in modern English for its clarity and ease of understanding. Consider your audience and context when choosing.
Is octopus a regular or irregular plural noun?
The Americanized plural, octopuses, is a regular plural noun form since it uses the -es. That said, octopuses is the American cough Noah Webster cough way to refer to more than one octopus. Octopi is the original Latinate plural, and uses one of the distinct Latin suffixes, i.e., -I. Octopi are in good company, and they are not the only Latin (or near Latin) words Modern English uses today.
| singular | plural |
| cactus | cacti (or cactuses) |
| octopus | octopi (or octopuses) |
| radius | radi (or radiuses) |
| fungus | fungi (or funguses) |
| alumnus | alumni (or almunuses) |
| 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
The thin skin of the octopus absorbs additional oxygen.
The Hawaiian day octopus (Octopus cyanea) lives on coral reefs; argonauts drift in pelagic waters.
The giant Pacific octopus (Enteroctopus dofleini) is often cited as the largest known octopus species.
The mouth of an octopus, located underneath the arms, has a sharp hard beak.
Each of the eight arms senses and responds to light, allowing the octopus to control the limbs even if its head is obscured.
Examples of “octopuses” in sentences
Octopuses live in every ocean, and different species have adapted to different marine habitats.
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.
Octopuses hide in dens, which are typically crevices in rocky outcrops or other hard structures, though some species burrow into sand or mud.
Octopuses are not territorial but generally remain in a home range; they may leave in search of food.
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. (Wikipedia, octopus).
Work Sheet
According to the blog post, which of the following lists contains the three correct plural forms of “octopus”?
Which plural form of “octopus” does the post state is most common and generally preferred in modern English?
The post explains that the plural form “octopi” follows the pattern of Latin words like “cactus” and “fungus”. However, the word “octopus” actually originates from which language?
Based on the classical grammar of its original language, the plural form of “octopus” would be “octopodes”. Which language is this plural derived from?
The post indicates that using “many octopus” is incorrect. What kind of noun is “octopus” in its singular form?
I saw several swimming in the tank.
The aquarium boasts a collection of magnificent from around the world.
While follows the pattern of Latin plurals, the word “octopus” is actually from Greek.
The classically correct Greek plural, , rarely appears and sounds arcane to most modern ears.
Most online dictionaries only recognize as the plural of octopus.
Frequently Asked Questions
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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Yash, D. "What’s the Plural of Octopus? Octopi? Octopodes?." Grammarflex, Jun 17, 2025, https://www.grammarflex.com/whats-the-plural-of-octopus/.
Sources
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Wikipedia, octopus.
