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Is the plural of virus "viruses" or "virii"?

tchrist
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Claudiu
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    Definitely not "virii" — the only plurals that end in '-ii' are those of words ending in '-ius'. "Virii" could only be the plural of 'virius', and only under the right circumstances. – ShreevatsaR Oct 08 '10 at 19:39

2 Answers2

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Wikipedia has a rather large section dedicated to this question. The verdict is: “The English plural of virus is viruses, not viri.” Merriam-Webster agrees, as does TheFreeDictionary. Wiktionary offers the following usage notes:

The plural is often believed to be viri or even virii, but neither is correct Latin and both are neologistic folk etymology. The word has no plural in Latin as it is a mass noun, like oxygen or sunlight.

tchrist
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RegDwigнt
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    +1. Plus we are free, in English, to form plurals in the English way if we want :) – Mr. Shiny and New 安宇 Oct 08 '10 at 19:44
  • @Mr. Shiny and New: I wholeheartedly agree, as does that Wikipedia article: "Even if the Latin plural were known, English speakers would not be obliged to use it". (It even proceeds to expressly mention campus and bonus.) – RegDwigнt Oct 08 '10 at 19:52
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    I guess I don't understand the distinction between a "known" plural and a "used" plural. English speakers -- who are not Latin speakers -- don't "know" declensions of Latin nouns. What they know is productive morphology in contemporary English for forming plurals.

    What are the "known" plurals of these words? Kindergarten-opera-blitzkrieg-tsunami-tycoon-phobia. All of these are foreign borrowings, which have "known" plurals in their respective languages of origins. But we don't pretend in English to be importing both the word and its plural forms. So why do we with Latin words?

     – Mike Pope Oct 08 '10 at 20:48
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    @Mike Pope: http://www.smbc-comics.com/index.php?db=comics&id=1981 – Claudiu Oct 08 '10 at 22:14
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    @Mike Pope: English has certain ways to form plurals. But sometimes the word AND its plural WERE imported by the early users of the term. Consider a medical term imported or coined from Latin. If the medical community imports (or coins) the word AND its plural together, and use the Latin forms in English contexts, then we have two new English words. When those words escape medical-jargon into the language as a whole, then the plural will be a Latin plural. – Mr. Shiny and New 安宇 Oct 12 '10 at 14:53
  • "When those words escape medical-jargon into the language as a whole, then the plural will be a Latin plural". A fair assessment of how (e.g.) Latin plurals end up in English, correct or otherwise. I would qualify this to say that the Latin plural is a plural, and might for a time be the only plural, but that standard English morphology has an excellent (and legitimate) chance to assert itself over time. And in any event, any such imported plurals would not be considered productive, right? – Mike Pope Oct 13 '10 at 01:40
  • ... which gets back to the original question -- the only really legitimate plural of virus in English is viruses, no? Certainly in the vernacular.

    (BTW, the question about the plural of opera is a bit of a trick question -- opera is the plural of opus.)

     – Mike Pope Oct 13 '10 at 01:43
  • I normally say "viruses" but just got smacked for saying "aquaria." –  Jan 17 '13 at 02:27
  • There's a very good reason that the citizens of the Roman Empire didn't have a word for the plural of "virus"-- they had no idea that viruses (or bacteria) ever existed. The Roman Empire was long gone before microbiologists ever discovered the presence of these microbes in our environment. Having said that, it's curious that "bacterium" has been accepted into usage as the singular form of "bacteria". This looks suspiciously like a case of retrospective validation: a case of linguists speculating what the Romans would have used as a singular form had they known that bacteria resided all around –  Feb 26 '15 at 23:13
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Speaking as a descriptivist, I would have to say that "virii" does indeed exist, in English rather than bad Latin, but only as a whimsical or jocular form (and particularly in an IT context). Strictly "viruses" for an unmarked usage.

Albert Herring
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    Some of those uses are whimsical or jocular and some are hypercorrection. I know I used to say "viri" (and write "virii") before I learned that I didn't need to do that to be "correct". – Mr. Shiny and New 安宇 Oct 12 '10 at 14:55
  • Fair comment. I think I first encountered it in a job lot with e.g. boxen and Elvii (cf the jargon file/hacker's dictionary), so the wilfully whimsical style of use was fairly clear from that - I shouldn't universalise my own experience. – Albert Herring Oct 13 '10 at 20:54