[Aardwolf]

So the plural of virus, if it wouldn't have been viruses, would be viri, not virii? I think for octopus I'd have intuitively thought octopi, but for virus I'd have thought virii.

[jjk166]

Virus actually is a latin word, but the plural is vira.

https://en.wiktionary.org/wiki/virus#Latin

[Rebelgecko]

The plural of the Latin virus is vira (second declension etc etc). However viri means "men"

[nerdponx]

It is in fact "viri".