Science in Esperanto: The Register That Almost Won

In September 1922 the Third Assembly of the League of Nations adopted a report on Esperanto. It is a friendly document, written by people who wanted the language to succeed, and it contains one sentence that is worth more than the whole rest of the file:

What it still lacks is technical vocabularies for several important sciences. There already exist Esperanto vocabularies for chemistry, pharmaceutics, mechanics, navigation and botany, but there are not any for electricity, physics and geology. The Esperanto Academy should have these vocabularies prepared at once.

At once. That was a hundred and four years ago, and the work was never finished.

This article is the honest account of Esperanto as a scientific language: what the ambition was, what machinery the language actually has for absorbing scientific vocabulary, which institutions existed and which of them are still breathing, how measurement reads aloud, and what a learner can genuinely read this week. It ends in a place that surprised me while writing it, so I will not spoil it here.

The ambition, and how close it got

The case for an auxiliary language of science was strongest in exactly the period when nobody could agree which one to speak. Around 1900 a European scientist needed French, German and English, and the reading load was a real tax on real work.

The League of Nations report catalogues the position as it stood in 1922, and the details are better than the folklore:

• An eminent body like the British Association of Sciences, having examined proposals and rejected Latin, concluded that Esperanto and Ido were both linguistically suitable and declined to choose between them.
• The French and Italian Associations of Sciences came down for Esperanto.
• In a dispute between the Hungarian and Czechoslovak Academies of Sciences, Esperanto was used as the language of official correspondence.
• Since 1920, the report claims, a new book in Esperanto on a scientific or other subject had been appearing every other day.

And the piece of this story that gets exaggerated most often, stated exactly as the primary document states it:

A petition was presented in 1921 by 25 members of the French Academy of Science asking that Esperanto should be taught in technical schools.

That is what happened. Among the twenty-five named supporters was Charles Richet, who had taken the Nobel Prize in Physiology or Medicine in 1913 for his work on anaphylaxis. So there is a genuine Nobel laureate in the story, once, on a petition about the school curriculum.

What you will read elsewhere is that Nobel laureates petitioned for Esperanto to become the language of science, or that the French Academy of Sciences recommended it for international scientific communication. Neither is what the document says, and this site is not going to print them.

The machinery: Rule 15 and the whole-word import

Before the institutions, the grammar, because the grammar is the part that actually worked.

Esperanto's method for scientific vocabulary is not word-building. It is Rule 15 of the Fundamenta Gramatiko, and here it is in the Fundamento's own English column:

The so-called "foreign" words, i. e. words which the greater number of languages have derived from the same source, undergo no change in the international language, beyond conforming to its system of orthography. Such is the rule with regard to primary words, derivatives are better formed (from the primary word) according to the rules of the international grammar, e. g. teatr'o, "theatre", but teatr'a, "theatrical", (not teatrical'a), etc.

Two instructions, and the second is the one everybody forgets. Import the base word whole. Then derive from it with Esperanto, not with the source language's grammar.

Which is why the scientific vocabulary of this chapter's own frequency band arrives finished, needing nothing built:

If you have read any science in English, French, German, Spanish or Russian, you already know several hundred Esperanto words and have not noticed. This is the single largest free gift the language gives an educated adult, and it is worth naming as a gift rather than taking it for granted.

The cost is on the other side of the ledger, and it is the subject of the next section.

The formants that are not affixes

Biologio contains something that looks exactly like a suffix. So does psikologio, and matematiko, and nervoza, and bronkito. Learners who have just mastered -ejo and -ilo see these and reasonably conclude that Esperanto has an -ologio and an -ik- and an -oz-.

The short answer is on the affix-like roots page: the international formants are not on any official list, and you may not coin new ones and expect to be understood. The long answer, with the exceptions and the technical registers where they really do work, is in the companion article on unofficial affixes. What belongs here is the science-specific part.

-ik- is the worst offender, because so many -ik words really are names of fields: fiziko, matematiko, botaniko, dinamiko, fonetiko, optiko, logiko, genetiko, tekniko. And then so many others are not: formiko is an ant, persiko is a peach, maniko is a sleeve, trafiko is traffic. PMEG's judgement is that promoting -ik- to a real suffix would make dozens of existing words appear to mean something they do not, and its instruction is oni lasu ĉi tiajn internaciajn vortojn en paco - leave these international words in peace.

-ologi- and -olog- are the exception, and a narrow one. PMEG does list them as genuinely usable unofficial suffixes, which is how esperantologio exists as a word for the scientific study of Esperanto, and kancerologio and kancerologo alongside oncology. The constraint is that an international word must already end that way. There is no *kuirologio* for cookery.

-oz- is medicine's, and does real work there: tuberkulozo, sklerozo, mikozo, and productively viruso to virusozo, a viral disease. It also has a chemistry job so precise it is easy to miss: -oza marks the lower valency of a metal with two series of salts, as in feroza sulfato. And it sits inert inside nervoza, which is a mood and not a condition of being full of nerves.

-it- is inflammation: bronkito, dermatito, encefalito, and productively orelo to orelito, an ear infection.

There is one more piece of this story, and it is my favourite thing in the whole subject, because it is the moment the language visibly bent its own vocabulary to protect its morphology.

Esperanto's -in- marks a female. That means any imported word ending in -ino risks reading as a female something. Heroino ought to be a female hero, and it is also the drug. Urino ought to be a female aurochs. So for a run of international words, the language quietly changed the vowel to dodge the collision:

azeno, delfeno, ermeno, frakseno, jasmeno, rosmareno, rubeno, sukceno, tendeno, plateno

A donkey, a dolphin, an ermine, an ash tree, jasmine, rosemary, a ruby, amber, a tendon, and platinum. Every one of those is -eno where the source language had -ino, purely so the affix system would not misfire. PMEG notes that alongside the Fundamental plateno the form platino has existed from the beginning with the same meaning, and both are perfectly good words.

That is a designed language protecting a rule at the cost of its own transparency, in the middle of the scientific vocabulary. Nobody advertises it and it is one of the most interesting decisions in the whole apparatus.

Measurement, read aloud

Here the news is straightforwardly good, and this is a section almost no Esperanto course covers.

The SI prefixes are used exactly as they are internationally. PMEG lists the full set, from kveta- at ten to the thirtieth down to kvekto- at ten to the minus thirtieth, and they attach only to actual units of measurement: metro, gramo, ĵulo, sekundo, litro, ampero, volto, bito.

Three details worth having.

Several of these words are already official. PMEG names them: kilogramo, decigramo, centigramo, miligramo, decilitro, centilitro, kilometro, centimetro, decimetro, milimetro. They belong to the Universala Vortaro or an Oficiala Aldono, which means the metric system is inside the part of Esperanto nobody may argue with.

One prefix has died and left a fossil. There used to be a miria-, meaning ten thousand. It produced miriametro, ten thousand metres, and that word even became an official Esperanto root. Neither the prefix nor the word is used any more. An official word can simply stop being spoken, which is a useful thing to know about what official means.

Two forms are irregular and are treated as separate roots: hektaro, a hundred ares, and megomo, a million ohms. The regular hektoaro and megaomo are also usable.

Saying a measurement

PMEG's table of how to read numbers aloud is the most practical page in the book and I have never seen it in a course. The essentials:

• Esperanto uses a decimal comma, and reads it as komo. So 12,34 is dek du komo tri kvar. And 46,987 is kvardek ses komo naŭ ok sep, digit by digit, never komo naŭcent okdek sep.
• A distance can be read two or three ways. 9403,5 km is naŭ mil kvarcent tri komo kvin kilometroj, or naŭ mil kvarcent tri kaj duona kilometroj, or naŭ mil kvarcent tri kilometroj kaj duono.
• Sub-units can be split out or left implied. 8,6 kg is ok komo ses kilogramoj or ok kilogramoj kaj sescent gramoj, and you may say tri kilogramoj kaj sepcent if the context makes the unit obvious.
• The slash in a rate is read with po at the front of the whole expression. 120 km/h is po cent dudek kilometroj en horo or po cent dudek kilometroj hore. 20$/kg is po dudek dolaroj por kilogramo. The tricky prepositions article has po in full, and this is its most useful everyday job.

A warning attached to that last point, because it is one Zamenhof gave himself. Po marks the rate, not the unit, so it goes at the front:

Oni ne povas diri "je 80 centimoj po funto" [...] sed oni devas diri "po 80 centimoj por (ĉiu) funto".

The Akademio has said the same. Getting this wrong is the commonest error in written Esperanto prices.

And the arithmetic, since numbers does not carry it:

Faras is the Fundamento's own verb for the equals sign; estas and egalas al are commoner today.

The institutions, and which of them are alive

Now the part that gives this article its title.

ISAE

The Internacia Scienca Asocio Esperantista dates itself to 1906, which makes it the oldest specialist association in the movement, and the UEA still lists it that way on its own directory of affiliated bodies. The date is a little soft: the association's own Vikipedio history describes 1906 as preparation and discussion at the second Universal Congress in Geneva, with the constitutive meeting at Cambridge in 1907, Zamenhof in the honorary chair. A 2006 article in Scienca Revuo was literally titled Kiam estiĝis ISAE? - when did ISAE come into being - which tells you the movement has not settled it either.

Its first officers, as recorded in ISAE's own bulletin: president Professor Ad. Schmidt, general secretary René de Saussure, and among the vice-presidents J. J. Thomson, the physicist who discovered the electron. I flag that one, because it appears only in Esperanto-movement sources and English-language accounts of Thomson's life do not mention Esperanto at all. It may be true. It is not corroborated, and this site says so rather than repeating it as a headline.

Today the UEA's directory gives ISAE 95 members and a website at scienca-asocio.com. That domain no longer resolves.

Scienca Revuo

Scienca Revuo appeared from 1949, quarterly, as ISAE's journal, continuing the Internacia Scienca Revuo which had run from 1904 to 1923. Its last issue was number 232, in 2015. Its Vikipedio article is written in the past tense and its own summary is one sentence: La revuo ne aperis ekde 2015.

The earlier journal's epitaph is better, and it was written in 1929, by Petro Stojan in his bibliography of the international language:

Fondita por sciencistoj tiu gazeto iom post iom pleniĝis je artikoloj de amatoroj, lingvaj diskutoj, reformaj polemikoj, fremdaj al scienco.

Founded for scientists, the magazine gradually filled up with articles by amateurs, language quarrels and reform polemics, alien to science.

That is the failure mode of a scientific journal in a movement language, diagnosed by a friend of the movement, seven years after the League of Nations report. The journal about physics became a journal about Esperanto.

The terminology bodies

Two of them, and this is the thread that actually leads somewhere.

ISAE's Terminologia Sekcio, led by Rudolf Haferkorn from 1957 to 1970, worked with the Akademio on the technical portion of the Plena Ilustrita Vortaro. That is real, lasting work: if you look up a technical term in PIV today, some of it comes from there.

The Terminologia Esperanto-Centro was founded in 1987, at the seventy-second Universal Congress in Warsaw, as an organ of the UEA, on the initiative of Wera Blanke with Humphrey Tonkin. Its brief was to unify technical terms, advise on terminology work and support the writing of specialist dictionaries.

You will find English-language sources saying the centre is still active. It is not, as far as anything checkable shows: its website has gone, the UEA's current directory of specialist bodies does not list it, and its own Vikipedio article is written throughout in the past tense. Treat it as dormant.

Eugen Wüster, and the thing the movement undersells

And then there is the fact that turns this article from an obituary into something odder.

Eugen Wüster (1898 to 1977) was an Austrian industrialist who became keen on Esperanto at fifteen. Between 1918 and 1920, in his early twenties, he compiled the Enciklopedia Vortaro Esperanta-Germana, a large Esperanto-German dictionary. He is also the man who coined the words esperantologio and planlingvo.

The experience of building that dictionary - of deciding, thousands of times, what a technical term is and how it should relate to its neighbours - became the basis of his 1931 Stuttgart doctoral thesis on international standardisation in technology, and that thesis is generally reckoned the founding work of modern terminology science.

The rest follows from it. Wüster took over the secretariat of ISO/TC 37, the international standards committee on terminology, in 1951. He edited the first International Electrotechnical Vocabulary in 1938. He initiated the founding of Infoterm in 1971. And Infoterm's members page today still lists the Universala Esperanto-Asocio, along with the Esperanto Museum of the Austrian National Library and the Eugen Wüster Archive.

He was also rector of the congress lecture series in 1970, which is a pleasing detail.

So the honest scorecard is not that Esperanto failed at science. It is that Esperanto did not become the language of science, and instead produced the discipline that organises the vocabularies of every other language of science. The auxiliary language lost the war and won an argument nobody was having.

What is actually alive

Five things, and a learner can use four of them this week.

The Esperanto Vikipedio. 389,037 articles when this was written, which puts it around 38th among the language editions, ahead of Uzbek and just behind Hebrew. The number flatters it, as the Esperanto today article says at length: many articles are short, and the active editor base is a few hundred people. For a reader none of that matters. It is the largest body of free non-fiction Esperanto prose in existence and it is written plainly by necessity.

Monato. Published monthly by the Flandra Esperanto-Ligo in Antwerp, first issue January 1980, still appearing. Its sections include Scienco, Medio, Moderna vivo, Politiko, Libroj and Literaturo, and its house rule is genuinely unusual: it prints only articles originally written in Esperanto and not published elsewhere. That makes it the closest thing the language has to a native press rather than a translation service.

Le Monde diplomatique en Esperanto, at eo.mondediplo.com, with an archive running from 1999. Be clear about what it is: a selection, a handful of pieces a month against a French issue of around fifty, published on the web with occasional print runs. Its translation policy is published, and it is the terminology gap made operational:

Ĝenerale, por tradukado ni limigas nin al la vortprovizo de la Reta Vortaro (REVO) kaj de la (libroforma) Plena Ilustrita Vortaro (PIV). [...] Se necesas uzi vorton ne troviĝantan en REVO aŭ en senco ne menciita en REVO (nek en PIV), ni aldonas klarigon en piednoto.

In general, for translation we limit ourselves to the vocabulary of ReVo and PIV. If it is necessary to use a word not found in ReVo, or in a sense not mentioned there, we add an explanation in a footnote.

A working publication that must footnote every term outside the dictionary. That is exactly the condition the 1922 report described, still in force, and being managed honestly rather than papered over.

The Internacia Kongresa Universitato. A series of specialist lectures at the annual Universala Kongreso, running unbroken since 1951 (as the Internacia Somera Universitato; renamed IKU in 1981, at the Brasília congress, because that one fell in the southern winter). Since 1997 the lectures have been published as a booklet, and the UEA hosts downloadable volumes for most years since 2006. Rectors have included Wüster in 1970, Claude Piron in 1979 and the economics laureate Reinhard Selten in 1999. It is science communication with published proceedings, not a venue for original findings, and it is a good read.

STEB, the Scienca kaj Teknika Esperanto-Biblioteko, a bibliography and article archive organised by subject class, holding the runs of Scienca Revuo, the conference proceedings and the terminology lists. Its own mission statement is a nice piece of movement self-awareness: La ekstera mondo prijuĝas la prestiĝon de Esperanto laŭ ĝia scienca kaj teknika aplikado - the outside world judges Esperanto's prestige by its scientific and technical application.

There is also KAEST, a biennial conference on applications of Esperanto in science and technology, first held in Žilina in 1978 and organised by E@I since 2010. Its last confirmed edition was 2024.

And the verdict on original research

Essentially none, and the word essentially is doing honest work.

• The flagship journal stopped in 2015, and its publisher has ninety-five members and a website that does not resolve.
• The one live refereed title in the movement's orbit, Medicina Internacia Revuo, published from the Jagiellonian University in Kraków and founded in 1923, now runs in English: titles, abstracts and metadata are English throughout, and a full text labelled Esperanto appears perhaps once a year.
• Everything else alive is presentation, translation, popularisation or bibliography.

So: a learner can read popular science in Esperanto today, with pleasure, and there is more of it than the sceptics allow. A researcher cannot publish in it in any meaningful sense, and has not been able to for a decade. Both halves are true and the movement's own literature tends to print only the first.

Why English won is a longer story than Esperanto, and it is told properly in Michael Gordin's Scientific Babel (2015), which is about the displacement of French, German, Latin and Russian as much as of the auxiliary languages. But the Esperanto-specific part of the answer is in the 1922 report and in Stojan's 1929 verdict, and it is not mysterious. A language of science needs vocabularies, and vocabularies need funded committees, and Esperanto's ran on subscriptions and goodwill. The report said to prepare them at once. Nobody could pay for it.

What to take away

• The 1922 League of Nations report is the best primary source, and it is candid: Esperanto then had technical vocabularies for chemistry, mechanics, navigation, pharmaceutics and botany, and none for electricity, physics or geology.
• The famous petition is real but smaller than reported: 25 members of the French Academy of Sciences, in 1921, asking for Esperanto to be taught in technical schools. Charles Richet, Nobel laureate of 1913, was among the named supporters.
• Scientific vocabulary enters under Rule 15: import the international word whole, then derive from it with Esperanto affixes. Teatro but teatra, not teatricala.
• So kemio, biologio, psikologio, galaksio, geno, maso, kvadrato and poluso are single roots, and the -ologi-, -ik- and -oz- inside them are not affixes you may reuse freely.
• The exceptions are narrow: -olog- and -ologi- do work where an international word already ends that way (esperantologio, kancerologio), and -oz- and -it- work inside medicine.
• Esperanto respelled a run of scientific words to protect its own -in- suffix: plateno, sukceno, rubeno, tendeno, delfeno, azeno.
• The SI prefixes are used exactly as internationally, and ten of the resulting words (kilometro, centimetro, kilogramo, miligramo and the rest) are official Esperanto roots. The dead prefix miria- left the official but unused miriametro behind.
• Decimals use a comma read as komo; rates use po at the front (po cent dudek kilometroj en horo); powers are kvadrate and kube.
• ISAE dates itself to 1906 and has 95 members and a dead website. Scienca Revuo ran 1949 to 2015 and stopped. The Terminologia Esperanto-Centro was founded in 1987 and is dormant.
• Eugen Wüster built an Esperanto-German dictionary between 1918 and 1920, wrote the founding work of modern terminology science out of that experience in 1931, ran the ISO/TC 37 secretariat from 1951 and started Infoterm in 1971. He coined esperantologio and planlingvo.
• Alive and readable today: Vikipedio (389,037 articles), Monato (monthly since 1980, science section, only originally-written Esperanto), Le Monde diplomatique en Esperanto (a selection, archive from 1999), the IKU lectures with published proceedings, and STEB as an archive.
• Original research published in Esperanto: essentially none. The one live refereed journal in the movement publishes in English.

See also

• The unofficial affixes - -oz-, -iv-, -it-, -olog- and the rest of the shadow system this article samples.
• Apposition and affix-like roots - the false-decomposition trap that the international vocabulary sets for every learner.
• Who decides what is correct Esperanto? - the Fundamento, the Akademio and what makes kilometro an official word.
• Esperanto hodiaŭ - the wider picture of where the language actually lives, Vikipedio included.
• The ĥ question - why chemistry is kemio rather than ĥemio, and what the Akademio did about it in 1974.
• Tricky prepositions - po in full, which is the preposition every price and every rate needs.
• Numbers - the counting system these measurements are built on.
• False friends - because an international-looking word is not always the word you think.