Plural of octopus
What is the plural of octopus? Is it octopi or octopusses?
We would go with "octopuses," a perfectly legitimate English plural form, and the oldest attested to. "Octopi" is also an acceptable plural, and one in wide use, but you run the risk of being informed that it's incorrect. Well-meaning people may tell you that -i is a Latin plural, but the word octopus isn't a Latin word. It comes from the Greek "oktopous," meaning eight feet. The word was latinized as "Octopus" then eventually became an English word. While the plural is irregular, it's hardly out of bounds.
Grammarians who don't like "octopi" sometimes suggest that the correct plural is "octopodes" or "octopods." The "pous" in octopus is a relative of "pod," a Greek word for "foot." The correct Greek plural for "pous" is "podes." But, nobody ever uses "octopodes" outside of arguments about the plural of "octopus." Nor should you.
In short, stick with "octopuses" unless you really prefer the sound of "octopi."