[Confusion]

Offtopic, but please, don't use 'virii'. The correct plural is 'viruses'. 'Virii' is wrong for two reaons:

1) The Latin plural of word ending in -us is not -ii. -i at best.

2) 'Virus' doesn't have a Latin plural, because its meaning is like (in the sense of not having a plural) 'sand': it already denotes a multitude.

[DrJokepu]

Being a Latin geek myself I can't help but point out that nouns in the fourth declension (u stem) also end in -us in singular and receive an -us affix in plural as well.

"Virus" is however, in the second declension (virus -i n. "slime, poison, goo") with the oddity of being neutral while having a second declension -us ending which is normally a feature of masculine nouns. And indeed, its plural would be "viri".

[nertzy]

Neuter nouns of the second declension don't generally have plurals that end in -i, but rather in -a, so "vira" would be equally possible.

It's also important to note that scholars don't actually know the proper plural of virus because they haven't really found one in extant literature.

Wikipedia has a longer discussion at http://en.wikipedia.org/wiki/Plural_of_virus#Virus

[mistermann]

Doo doo doo doo, doo doodoo do, Doo doo doo doo, doo doodoo do, Doo doo doo doo, doo doodoo do, Doo, doodoodoo, doo doo doo doo doo....

A bit hard to communicate, but that's the keyboard cat playing all of you off.

[gmazzola]

Ironically, I was very careful with my choice of "virus vs. virii" when I wrote that message. I looked up the Wikipedia article for Plural of Virus ( http://en.wikipedia.org/wiki/Plural_of_virus ), and noted the sentence "In reference to a computer virus, the plural is often believed to be virii...".

As an amateur Latin geek myself, I agree that "viruses" is proper from a grammar standpoint, but I sided with Wikipedia because I was using computer terminology.

[nopassrecover]

but if you read on.. "or, less commonly, viri, but both forms are neologistic folk etymology[1] and no major dictionary recognizes them as alternative forms."

[sev]

Why is it that the plural of "radius" is "radii" but the plural of "virus" is not "viri"? I don't see "virus" as inherently denoting a multitude in the dictionary. Just curious.

[DrJokepu]

Because with [radi]us the stem is "radi" but with [vir]us the stem is "vir". These words are from the same type (second declension) they both receive an -i affix in plural, hence radi + i = radii, vir + i = viri. Latin being Latin there are an awful number of exceptions but this is a somewhat general rule.

Put it like this: Grammatically speaking, the plural of virus is viri. Putting it into plural might or might not makes sense. Personally, I don't think that using plural for collections in Latin is a very big sin given that this is very common in classical Latin texts.

One example of this can be found in the famous introduction of Aeneid (I.1 "Arma virumque cano...") lines 31-32, where Virgil is using the plural form of the word "sea" (mare, plural: maria)

"multosque per annos / errabant acti fatis __maria__ omnia circum" - "for a number of years, driven by fate, wandering around on the seas"

[thomaspaine]

Virus is Latin for poison. It's a mass noun because it denotes something uncountable (not in the strict mathematical sense, but in the how the hell do you count poison sense). As far as I know, there is no Latin plural form for virus.

Second declension singular nominative nouns end in 'us' and their plural form end in 'i', but fourth declension singular nominative nouns also end in 'us', but their plural form still end in 'us'. Also, like in every language, there are funky exceptions to these rules, like second declension singular nominative nouns which are neuter rather than masculine, but still end in 'us' rather than the normal 'um'. Moral of the story, don't assume that the plural of word ending in 'us' is 'i'.

It's also been about 8 years since I've taken Latin, so take that into consideration before someone goes all Life of Brian on me.

[psyklic]

Interestingly, English words with irregular forms which are infrequently used often revert back to regular forms. The 'why' is simply because people prefer to say "viruses," either because they forgot the irregular plural form or because they prefer how a regular form sounds.

[__david__]

And furthermore "sands" is still perfectly legitimate, even though "sand" may be inherently plural (the "sands" of time, different "sands" of the world).

[Tritis]

If the plural of goose is geese why is the plural of moose not meese?

[Sephr]

The correct term in Hixie English is virii. You need to learn your Hixie English (even the HTML5 standard is written in it).