The word theorem comes from late Latin theōrēma and the Greek θεώρημα . If one wanted a plural form other than theorems that reflected its etymology, what would it be? I understand the standard plural is theorems but I would still be interested to know.

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    Presumably theoremata, though that would be the plural of theorema, rather than theorem. Jan 29, 2014 at 14:09
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    There is a group of words that originate in Greek third-declension neuters in -(η)μα, and which in Greek have plurals in -(ῆ)ματα. Some have been borrowed directly from Greek or Latin as neologisms (stigma, zeugma, anathema) and to the extent that they form plurals, they often retain the Greek plural at least as an option (stigmata, zeugmata). Most, however, come via French and end simply in -m(e) in English (problem, theorem, diaphragm, biome). These invariably take simple English plurals and their connection to the Greek -(η)μα group is obscure and non-transparent. Jan 29, 2014 at 14:24
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    I disagree with the notion that stigmata is used as plural for stigma in English. At least nowadays, a stigma is most commonly used in the sense of a social stigma, where stigmata has a religious sense (the marks on the body of Jesus).
    – oerkelens
    Jan 29, 2014 at 14:26
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    @oerkelens, but the singular of ‘stigmata’ is still ‘stigma’. ‘Stigmata’ is one of the available ways of forming a plural of ‘stigma’ (though only in one sense of the word), whereas it is not an option at all to pluralise ‘problem’ as ‘problemata’, for instance. Jan 29, 2014 at 14:30
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    I doubt any modern English reader will normally ever read stigma as the singular of stigmata or vice versa. Yes, in a religious setting, discussing if a single mark is a stigma in the "stigmata"-sense, is is possible. But I have not encountered any headline about social stigmata affecting certain social groups... Purely grammatically the option is there, mostly because both stigma and stigmata are commonly known and even though they normally have a different meaning, they do not "sound" as "strange" as "problemata" would.
    – oerkelens
    Jan 29, 2014 at 14:34

4 Answers 4


It (strictly in Greek or Latin) would be theoremata, just like schemata. This is the general declension for several -ma words originating in Greek.

But this seems artificial, and in any case why would you want to use the Greek plural pattern when the English one does the job?

  • Thank you. To answer your question directly, only for linguistic amusement.
    – Simd
    Jan 29, 2014 at 14:11
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    I think linguistic amusement is a very valid reason :)
    – oerkelens
    Jan 29, 2014 at 14:30
  • It is curious that the Greek word theoremata only seems to exist in Latin texts. Why would people use a Greek plural when writing Latin?
    – Simd
    Jan 29, 2014 at 20:04
  • Because the Romans held the Greeks in high esteem and emulated them. You would know how many Greek words Cicero uses in his texts for example.
    – Å Stuart
    Jan 29, 2014 at 20:11
  • Maybe the reason why is related to the vowel ending in English?
    – Adalynn
    Nov 10, 2018 at 19:47

As noted in the other answers, "theorems" is the standard usage in math papers. In an odd contrast, however, "lemmata" still has some currency as the plural of "lemma" (an intermediate theorem), and crops up pretty regularly even in very recent papers. On the other hand, my (unresearched) impression is that this too has become less widespread in recent decades.

For comparison, a search for "lemmata" in the text of MathSciNet reviews gives 313 matches, while "theoremata" appears only six times, all in references to the Latin titles of very old papers.

  • I see lemmata is even listed in the OED as a possible plural form.
    – Simd
    Jan 29, 2014 at 19:42
  • To tell you the truth, I once wrote "lemmata" in a paper, and the referee commented that "lemmas" is the "21st century plural". (:
    – Mark G
    Jan 29, 2014 at 19:53
  • Google ngrams makes a nice picture for lemmata. I would paste it if I could.
    – Simd
    Jan 29, 2014 at 20:00
  • Well, "lemma" retains the Greek suffix in the singular, while "theorem" is anglicized by dropping the suffix. Perhaps the contrast between the plural forms seems less odd with that in mind.
    – herisson
    Sep 18, 2016 at 2:16

The accepted plural seems to be theorems. At least big dictionaries such as Collins or American Heritage Dic. give no other plural form. For some Latin or Greek word Latin and Greek plural-endings can be found but obviously not for all Latin/Greek words. That would be an over-academization of the vocabulary. And I think it is a good thing that foreign plural-endings are restricted to a limited number of words.


For Latin words the Latin plural is sometimes used, possibly because that language has been the lingua franca in science until very recently, which ensures we are familiar, at least in science, with both the singular and plural form in it's Latin original.

In case of Greek or other origins, I guess the plural reflecting the origins of the word would only be used it that plural denotes an individual concept in English, separate from the singular form.

Two examples I can think of are the Greek stigmata which is a plural meaning "signs" and the Arabic Tuareg (a plural meaning "paths" or "ways").


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