[Xenalyte]

No, that's for -ius, which "radius" is and "octopus" is not. "Octopus" takes one I to go plural - "octopi."

[Izzy Dunne]

No, that's for -ius, which "radius" is and "octopus" is not.

Which is just what I said.

Anyway, according to Dictionary.com, either is correct. So I withdraw my complaint, if the original poster withdraws his.

But the plural of "virus" is NOT "virii", as I have seen elsewhere. Consistency is not a virtue of the language....