When you see a bunch of octopus and your friends ask you how many there are, would you say you saw eight octopuses or octopi? Speakers of the English language are divided about the plural of the word octopus. Merriam-Webster Dictionary, Oxford English Dictionary, and American Heritage Dictionary affirm that both plural forms are correct, with octopuses as the primary accepted form and octopi as a variant. So where did the divide come from?
The word octopus closely resembles several other words with irregular plural forms: syllabus, fungus, stimulus, alumnus, etc., These words are all from Latin, and they undergo second declension, which means their plurals are formed by dropping the -us and replacing it with -i. Many wrongly assumed that octopus belongs to the same category and gave it the same pluralization. However, the word octopus is from ancient Greek instead of Latin, so it doesn’t make any sense that we should give this word a Latin declension. And if we are to be pedantic and give this word its ancient Greek plural, it’s octopodes, which people rarely know and use in the English language.
So how about octopuses? This is actually the standard English plural form of the word. As the word entered into the English language, it received the regular pluralization of a noun, where we add -s or -es at the end of the word, therefore, octopuses. So how about the other words mentioned above, how come they retained their Latin plural forms? Well, the answer really is we cannot expect English to be a regular language, given that it has taken what it can from where it can.
The question now is: which plural form of octopus do we use? We have three choices; we can:
- use octopuses and stick to the standard and correct plural form of the word, as all reputable dictionaries have established.
- use octopi and save ourselves from the judgmental look and sighs of people, despite it being misconceived and incorrect.
- use octopodes and be prepared to pedantically give them a lecture of how this is the appropriate plural form based on its Greek origin.