what is the plural of octopus?
Because the Latin irregular plurals are most common, and sound loftier than the regular plural, there is a tendency to hypercorrect the plural of any word ending in-us and-um in particular, even when there is no historical basis for it. And thus, Oxford tells us. The standard plural in English of octopus is octopuses. However, the word octopus comes from Greek, and the Greek plural form octopodes is still occasionally used. The plural form octopi is mistakenly formed according to rules for Latin plurals, and is therefore incorrect.