The following Latin/Greek singular vs. plural errors make me cringe every time:

  • bacterium - bacteria
  • criterion - criteria
  • millennium - millennia
  • phenomenon - phenomena

It's extremely typical for an English speaker to always use the plural form, i.e. "the bacteria replicates by...", "the criteria for ... is ...", "a nice millennia". I would go as far as to say that the incorrect use trumps the correct use, but maybe there's a slight bias because I started looking for it. Well, it's mostly on YouTube, but the speakers do have degrees or at least represent science channels. A well known physics professor even used "these phenomenon" along with "this phenomena". Super-cringe. Yes I listened back several times, because it's sometimes hard to hear the exact endings.

So much for the rant, the real question is: Have (some of them) become so common that they are considered acceptable? I can't really tell, because it's not my first language. Maybe I care more because of that.

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    The answer to this question, as to any other question whether some, originally incorrect, usage has become so common that it is considered acceptable, will depend on where one stands on the prescriptivism-descriptivism spectrum. As thoughtful, educated people are scattered along a large part of that spectrum, one cannot expect them to be unanimous in answering them.
    – jsw29
    Commented Sep 17, 2020 at 21:30
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    Exactly the same question can be asked about some Italian loan-words, such as panino/panini and biscotto/biscotti. It is quite common to hear people ordering 'one panini' or 'one biscotti'.
    – jsw29
    Commented Sep 17, 2020 at 21:33
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    English is not Latin. English is only English. (And Latin is dead anyway, so who is to say it wouldn't have developed by now to have no plurals at all. Or to have seven different ones to be used depending on the time of the day.) When you borrow a word, you borrow just the one word and not an entire dead grammar or alien morphology. Quick, without googling, what is the German plural for Kindergarten, Rucksack, or Zeitgeist. What is the Russian plural of sputnik or perestroika. What is the Japanese possessive of sushi. If you get any of them wrong, I promise to cringe every time.
    – RegDwigнt
    Commented Sep 17, 2020 at 22:01
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    @RegDwigнt Nice quiz, I got 5/6 right, because I hate sushi as much as possessiveness.
    – user399018
    Commented Sep 18, 2020 at 2:43
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    When I'm in a mood to "cringe every time", media vs. medium always works.
    – TripeHound
    Commented Sep 18, 2020 at 5:15

4 Answers 4


Many words borrowed from another language do not retain their prior language's number or case structure in English. Singular or non-count bacteria and criteria are frequently used with verbs in a singular form, and are at least somewhat assimilated into standard forms of English. Singular or non-count millennia and phenomena rarely appear with verbs in a singular form, and thus appear to still be anomalies.


It is possible to refer to a single strain as a bacterium (the Oxford English Dictionary lists bacteria under bacterium). Note, however, that bacteria is far more common in use than bacterium (Ngram):

enter image description here

The Corpus of Contemporary American English also has several results for "bacteria _VVZ" (bacteria with a verb ending in -s). The official status of some of these examples leads me to believe bacteria is an acceptable form of the singular in many uses:

The bacteria grows under fluorescent light. (Cain Burdeau. "LA scientist's oysters safe from oil, but pricey." Associated Press, 20 Aug. 2010.)

Bacteria grows, you ingest it, you become ill. It's no secret. ("Behind the Counter - Restaurant Filth Exposed." ABC Primetime, 27 Sept. 1995.)

What's frightening is that the vibrio bacteria occurs naturally in warm seawater, unrelated to pollution. (ABC 20/20, 9 February 1990.)

But if we do know that bacteria causes, you know, gum disease and cavities, why not just do something right there? ("Potential links between chronic disease and bacterial infections." NPR Science, 26 February 1999.)

AP, ABC, NPR - a lot of news organizations use bacteria with a singular verb, especially in spoken contexts. That leads me to conclude it is widely accepted in standard language, even if some prescriptivists still wince upon hearing it.


Criteria has become more common through the 20th century. enter image description here

It has also been used with -s verbs in publication and speech, with several significant results from COCA:

For example, the first criteria includes the use of creatine and artificial low-oxygen living environments. (Matthew Mitten. "Is drug testing of athletes necessary?" USA Today Magazine, vol. 134, iss. 2726, Nov 2005. )

The selection criteria includes academic achievement, leadership and community involvement, and students must graduate from one of the participating senior high schools in Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery or Waller counties. ("Katy American Little League^s Astros take first place in 8-year-old play." Houston Chronicle, 12 July 2000.)

The same criteria applies to next month's debates. (PBS NewsHour, 28 August 2019.)

So at least in some official uses, criteria used with a singular verb is acceptable.


The singular form remains more common, especially near the turn of the millennium. enter image description here

No significant results for millennia with -s verbs in COCA. In my experience, millennium is still overwhelmingly used for the singular.


The Ngram indicates more recent growth in the use of phenomenon compared to phenomena. enter image description here

In COCA, there are a couple of examples of publications using phenomena with an -s verb, but far fewer than for bacteria or criteria. I suggest that this remains uncommon, and phenomenon remains generally recognized as the singular form of the word:

I think it's fair to say that the phenomena exists from just off the coast of China all the way to a few hundred miles from the coast of California. (PBS News Hour, 13 November 2008.)

The tracking phenomena proposes that these V0 2 max levels at age 20 project the individual to be in the low-risk CVD category at age 45. (Bradley Cardinal. Cardiorespiratory fitness and physical activity behavior ..." Physical Educator, vol. 52, issue 4, winter 1995.)

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    So I was on to something after all. I completely understand that there is no need to retain the roots, but the ambiguous use over 'long' periods seems pretty strange. Do these numbers/graphs account for the fact that e.g. a larger percentage of written sentences involve criteria in the plural. Or that most people do not refer to individual bacterium most of the time?
    – user399018
    Commented Sep 17, 2020 at 19:18
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    It's probably an interesting topic in research: how much of language evolution is due to laziness/mistakes/etc. I would go for 95%, along with the bet that by 2050 "should of" is accepted use.
    – user399018
    Commented Sep 17, 2020 at 19:25
  • That little uptick at the end of the red line on the last graph.
    – mcalex
    Commented Sep 18, 2020 at 4:49
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    I don’t see the relevance of the charts. Surely all they show is the relative usage of the words. Perhaps they’re all used in the “prscriptivistly correct” manner, or perhaps not. All we can see is that the word “bacteria” is used a lot more. That makes sense: it’s more common to talk about many bacteria than one bacterium.
    – Tim
    Commented Sep 18, 2020 at 19:39

I agree with your opinion. The question of frequency of usage, although informative, is not the main issue. What matters is the creeping corruption of meanings. This not to do with pedantry but with the retention of useful words and the avoidance of unnecessary neologisms. If we name a singular thing by its plural we lose the capacity to talk of the single thing and we lose the capacity to discriminate between the plural and the singular. This, in the case of the Italian panino/panini misuse leads on to the gruesome plural paninis. Similarly, how long before a group of some of the professor's singular phenomena becomes his phenomenas?

  • Funny enough, M.W. actually lists phenomenas as the plural of the nonstandard singular phenomena, after mentioning professors, see merriam-webster.com/dictionary/phenomena
    – user399018
    Commented Sep 18, 2020 at 2:28
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    Oh no! The fifth horseman of the apocalypse has arrived.
    – Anton
    Commented Sep 18, 2020 at 6:53
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    We don't lose the ability to discriminate. We replace the original language's method with our own: "one bacteria" vs "many bacteria".
    – Barmar
    Commented Sep 18, 2020 at 16:10
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    Consider also that it's rare that most people ever need to refer to a single bacterium; we generally talk about them as collections (the bacteria in your gut) or as general concepts (bacteria can be harnessed to produce medicines).
    – Barmar
    Commented Sep 18, 2020 at 16:13
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    To be pedantic, what's the difference between pedantry and "avoidance of unnecessary neologisms"?
    – Dan Getz
    Commented Sep 18, 2020 at 19:37

Here are some interesting results (I found a new toy)

We live in uncertain times: Bacterium grows 50:50

The American-English stats, however, show that the bacterium seemed to die out, but was somehow revived:enter image description here

Not all hope is lost for Italian, too: enter image description here

The criteria also applies much less now than in the 1980s enter image description here

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    Please say what your "new toy" is. Is it Google ngram? Please always give links to graphs, pictures and quotes so we can check for ourselves. Commented Sep 18, 2020 at 15:32

We all make mistakes. Mistakes should be forgiven.

But I'm sure most style books do not consider these acceptable. A basic rule of style is as follows: do not use a 'sophisticated' word unless you know how to use it.

Certainly many pedants still cringe at seeing such mistakes, which is reason enough to say it is not acceptable, even if a large number of people in academia should fail to notice.

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    My intention was not to rub in mistakes, rather to understand if the examples are perceived/considered as mistakes at all.
    – user399018
    Commented Sep 18, 2020 at 2:31

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