There are many particle names ending in -on in English: electron, muon, lepton, proton… How should these particle names behave in Latin?

My impression is that the electron and the proton came first (I'm not sure of their naming order), and the rest were modeled on them. The electron is "amber" (ἤλεκτρον) and proton is "first" (πρῶτον). This makes me want to treat all these particles of second declension neuters of the Greek type, and I wouldn't be opposed to Latinizing them into electrum and protum if someone is so inclined.

However, Vicipaedia seems to treat these words as third declension masculines ending in -on/-onis. This feels off to me, especially with the final -n which I expect to be dropped from a Latin nominative of this kind. The Latin Wikipedia is not particularly reliable, but there might be a good reason for this convention. Perhaps the words were borrowed from English to Latin and assigned to the third declension without much etymological thought. Or this might be by analogy to Italian where the ending is -one (corresponding to the Latin third declension).

Etymological considerations and comparison with Italian seem lead to different Latin declensions. Vicipaedia also gives the alternative electronium. Yet another thing to consider is that the neutron might have a significant conflict with the pronoun neuter.

How do you think the particle names ending in -on in English should be treated in Latin? And, most importantly, why so?

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    The -on/-onis ending seems off to me too. I'd have thought electrum, protum, etc. would be the most obvious Latin forms. Perhaps it's merely to distinguish the word for electron from the word for amber, and then the other particles are named by analogy. I'm not sure that's a very compelling reason though; after all, how often does the word amber really come up? On a whim, I checked what the modern Greek words for electron and proton are, to see whether they've also been distinguished from the words for amber and first. Sure enough: ηλεκτρόνιο and πρωτόνιο, which I assume are diminutive forms.
    – cnread
    Commented May 23, 2017 at 21:48
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    @cnread Vicipaedia also gives the alternative electronium (which I only now remembered to add to the question). Many words have several different meanings, and the risk of confusing electrons with amber is minimal. If it seems to be a problem in some situation, one can always add words to clarify. I wonder if the suggestions in Vicipaedia are borrowed from (written by native speakers of?) Italian or Greek. I feel it's best to go directly from the Greek origin to Latin without passing through modern languages, but others might disagree.
    – Joonas Ilmavirta
    Commented May 23, 2017 at 21:57
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    Based on cursory (cough Etymonline cough) research, the "-on" in electron is by analogy with "ion," which itself is merely a transliteration ἰών, the present participle of Greek "to go." In that case, it would be misguided to act as if -on was a neuter 2nd declension ending. I found an old book called De iontum migrationibus electrolyticis to confirm that at least one person thought that way...
    – brianpck
    Commented May 24, 2017 at 0:47
  • The rule on Vicipædia is "noli fingere": they want a source or precedent for every word. Are you able to check the sources given in the Vicipædia article? (They're at the bottom in small type under Notae.)
    – Ben Kovitz
    Commented May 24, 2017 at 0:48
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    Everyone: There are very good observations and nice ideas in the comments. Please write your ideas into answers. An answer does not have to be perfect to be useful. I would much like to have the different ideas posted as answers, so that people can vote, comment, and develop the ideas further.
    – Joonas Ilmavirta
    Commented May 24, 2017 at 4:20

8 Answers 8


It is correct that ἤλεκτρον means “gold-silver alloy”, and then “amber”, and that it is the source of modern words like electricity, electric, electromagnetism etc. But I do not think you can say that “electron” is borrowed directly from ἤλεκτρον, especially as it does not have the same meaning. Rather it is a modern formation with the “particle” suffix -on. This started with the genuine Greek words anion “going up” and kation “going down”, both neuter participles of the verb “to go” with different prefixes: an- and kat(a)-. Then we got “ion” on its own as a term encompassing both, and then, by analogy, “proton”, “electron”, “neutron”, and ultimately also “positron” (the last of these based on a spurious reanalysis of electr-on as elect-ron, and creation of a pseudo-suffix “ron”).

So what to do in (Neo-)Latin? Perhaps reborrow the English “electron” as electron, -ontis?


To add another voice to this conversation, I would like to show the entries given for various particles in the Morgan and Silva Furman University Lexicon:

electron- electron, -onis; electronium, -i

proton- protonium -i

neutron- neutro, -onis; neutronium, -i

anti-neutron- antineutronium

anti-proton- antiprotonium

photon- photonium

quark- quarcium

For the most part, there seems to be a trend of adding -ium to the end of the particle's English name. Many of these words are source to the Latinitas Recens, so it seems somewhat credible. However, as for electron and neutron, there seems to also exist alternative forms that retain the more Greek origins. fdb suggests in their answer that the genitive form for this would be -ontis, however, this seems to be refuted by these entries, which drop the t. Joonas Ilmavirta makes a good point about how some of these terms may be confusing when one starts talking about other similarly named objects, but I feel as though, to use his example, protonium would not be translated as such. In the Wikipedia article he cites, it states that the other name for this particle is anti-protonic hydrogen. Perhaps this could instead be translated as antiprotonicum hydrogenium. Note here that even hydrogen follows the -ium rule.

It seems that there is evidence for -ium as the preferred ending to particles. However, there is still much to be discussed in the matter, as demonstrated by the many comments and answers to this question.

A few final notes:

  1. There are a few deviants to this pattern that I found, one of which was already discussed:

ion- ion, iontis

neon- neon, neoni

I'm not sure what to make of that, but I guess that's for you to figure out.

  1. Even in classical Latin there are examples of words that look exactly the same, and yet have different meanings. Although attempts should be made to avoid this moving forward, it is something we still have to deal with if it does occur. Just one example:


  • nominative or genitive singular meaning bird
  • dative or ablative plural meaning grandmothers/fathers

Obviously, the meaning could probably be deduced from context, and I think a similar line of thought could be used when talking about possible conflicts. So those are my two cents, do with that what you will!

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    From the point of view of a chemist, this would be somewhat confusing. The "ium" ending is associated with elements, not particles. Commented Aug 29, 2023 at 13:39
  • @RayButterworth No reason it couldn't be both? This is Latin, after all, not English. There are plenty of Latin nouns ending in -ium that aren't elements.
    – cmw
    Commented Aug 29, 2023 at 19:01
  • @cmw, it can be whatever it is. I'm just saying that chemistry has a naming convention, and this eliminates it. It's like "-ase" means enzyme, "-ose" means sugar, "-ol" means alcohol, "-ic acid" means fatty acid, etc. The conventions aren't necessary, but they are convenient. Commented Aug 29, 2023 at 20:59

My understanding is that the mother of all -on scientific terms is the ion, which is a Greek neuter participle (I'm told). Later -on coinings seem to be a play on the already understood word ion. Its natural Latinization, it seems to me, would be ion, iontis.

Mutatis mutandis, then, the genitives of your list of words would be electrontis, muontis, leptontis, protontis, etc.


There are reasons to treat them as (Greek style) second declension neuters. The Latin ending corresponding to the Greek -on is -um, and the names can be Latinized as electrum etc.

There was no word for an electron in Greek or any other language. One simply had to come up with a new word or borrow a word from a classical language and change the meaning — the latter method was certainly not unheard of in science. Picking ἤλεκτρον for the name of a negatively charged particle makes sense. Similarly πρῶτον can be chosen for the name of a positively charged particle.

These two words are second declension neuters in Greek, and are easily recognized as such. (Yes, πρῶτον has masculine and feminine words too, but the neuter forms are regular second declension.) Therefore it is most intuitive to treat them similarly as Latin words.

Similarity to the Greek participle ion may be seen as an accident. I see no problem declining ion as iontis while using the genitive electri for electron.

I would strongly advise against using forms like electronium, since there are established physical concepts with names like protonium. When confusion can be avoided, it should.


A contrarian suggestion: recall the conference in 1932 where two kinds of “neutron” were discussed, and Fermi said (in Italian) “let's call the heavy one neutrone and the little one neutrino,” suggesting that he at least fancifully feigned to understand –one as the augmentative suffix, which in Latin is –ō, –ōnis.

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    The Italian -one does seem to come from the Latin -o, but did it have an augmentative sense in Latin? See this question on augmentatives in Latin for details.
    – Joonas Ilmavirta
    Commented Aug 29, 2023 at 2:42
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    @JoonasIlmavirta Well there's the bignosed poet Publius Ovidius Naso. As a student I took that as ablative “with the nose” … unfortunately Latin Wikipedia does not provide stems for its lemmata :( Commented Aug 29, 2023 at 15:43

I will post some arguments in support of the electrōn, electrōnis (m.) convention.

  • It seems to effectively avoid ambiguity for most forms: electrōn, electrōnis, electrōnī, electrōnem, electrōne, electrōnēs, electrōnum, electrōnibus. Ray Butterworth and Joonas point out that the versions ending in -ōnium, -ōniī, such as prōtōnium, may cause semantic confusion with other terms that have different meanings. Using second-declension neuter versions, such as electron, electrī, leads as Joonas mentioned to ambiguity between many forms of neutron and of neuter, neutra, neutrum, which seems undesirable.

  • It seems more straightforward and less "fanciful" in my view than using the participial declension in -on, -ontis. (I don't feel strongly averse to using stems in -ont- for particle names, but to me it feels like it has a bit of the flavor of using "octopodes" as the plural of "octopus" in English.)

My response to the objection that Latin third-declension nouns do not usually have a nominative form ending in -ōn is that this is not an inviolable rule, but simply the norm that historically developed for native Latin words. Words borrowed from foreign languages were often adapted to the Latin pattern, but not invariably so. Given that for most people living today, the most familiar forms of these particle names (and related words such as electronic) feature an ending containing the letter N, it seems preferable to me to retain this letter rather than removing it when using the names in Latin. We can view it as a borrowing into Latin from modern scientific terminology. Even if this creates a somewhat unusual declension pattern, it is at any rate not an entirely unprecedented paradigm: compare Babylōn, Babylōnis (f.) and Calydōn, Calydōnis (f.).

I think clarity and recognizability are more important and more achievable goals in this context than etymological accuracy.

Many of the advantages I mentioned apply also to similar third-declension variants, such as electrōn, electronis (modeled, rather arbitrarily, after the paradigm of canōn, canonis) or electrō, electrōnis.

  • Just to be sure: Is a third declension version of the original Greek electron attested? It does make some sense to divorce from etymology in favor of unified and practical particle names, but maybe that statement should be made explicit.
    – Joonas Ilmavirta
    Commented Sep 3, 2023 at 10:54
  • @JoonasIlmavirta: As fdb said, the particle name "electron" seems to not have any original Ancient Greek form, because it was coined in the modern era as a blend of "electric" and "ion". The Oxford English Dictionary actually has two separate entries for electron n² (the particle name) and electron n¹ (electrum, the mix of gold and silver = ἤλεκτρον).
    – Asteroides
    Commented Sep 3, 2023 at 11:42

In my YouTube video about afterlife in Latin, I used "particulae electricitatis" for "electron":

Multi homines huius temporis dicunt physica quantorum arguere pro vita post mortem. Sed ego censeo physica quantorum arguere contra vitam post mortem. Si non contra omnes formas vitae post mortem, tunc contra formam vitae post mortem in quam plurimi homines credunt. Plurimi homines imaginantur animas, et ut eae animae quodam modo possint videre, sed eae animae non possint videri ab aliquibus machinis. Sed physica quantorum docet nobis quod passivi observatores non dantur. Particulae electricitatis agunt ut undae cum non spectantur, sed eae agunt ut particulae cum spectantur. Si animae existunt quae possunt videre, eae animae possint videri ab aliquibus machinis. Ergo, forma vitae post mortem, in quam plurimi homines credunt, ea contradicit firmissimae scientiae, quae est physica quantorum. Ego censeo solum modum, quod eam problemam evitat, monades Gottfriedis Leibnizis sunt. Gottfried Leibniz enim censebat rem extensam et rem cogitantem non interagere, sed solummodo apparere interagere. Sane, novacula Occami tunc arguit contra existentiam rei cogitantis.

I think that's the phrasing that's the least likely to cause a confusion.

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    Thanks! This is a useful circumlocution for some contexts, but in physics a "particle of electricity" would be ambiguous. When there is an electric current, the particles that move are not always electrons, and in my first reaction to the term would be a photon, the carrier of the electromagnetic force. But I know full well that I'm biased as a physicist, and many others will react to the term differently.
    – Joonas Ilmavirta
    Commented Aug 29, 2023 at 17:08

Greek names like Platon, Oxford Platonis opera, Ion, Charon, Kimon, Jason with were so common in the Latin speaking world, so there is no need to introduce something else like protium or photium as given names by the fathers of the elementary particle world.

The chemical world consists of -iums, mostly to denote substantial orgin as in sodium (from German Soda, German natrium from french/engl. natron, arabic from gr. nitron) or personal origin as eg. in Curium.

  • The ending -on (and especially the inflected forms) in the Greek words Platon and electron are different. If I'm interpreting your answer correctly (which may or may not be the case), you seem to be conflating the two -on endings. How would you decline the word electron in Latin? Electri or electronis in the genitive?
    – Joonas Ilmavirta
    Commented Aug 31, 2023 at 11:25
  • In quantum statistics all elementary particles of the same 'name' are indistinguishable. Any of those invisible little entities called elementary particle has a counterpart, its antiparticle. Feynman ascribed to them that they move backwards in time, perhaps a mathematical trick. So he proposed, that there is only one single electron and one single proton in the whole universe of which we observe different parts of its trace. Conclusion: the electron as a name may be different from its greek origin, a silver-gold gold mixture, that would translate into electronium by Latin writing chemists.
    – Roland F
    Commented Sep 1, 2023 at 8:06

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