Ido

Ido is an international auxiliary language, a constructed language of the reformed-Esperanto type, created in 1907 by a group of European scholars on the basis of an anonymous project whose author used the pseudonym "Ido" (ido in Esperanto means "descendant"), which then became the name of the language¹. It was designed as a revision of Esperanto intended to remove features its reformers saw as obstacles to easy learning, and it remains one of the most prominent of the languages descended from Esperanto.

Origin: the Delegation and the reform project

The Delegation for the Adoption of an International Auxiliary Language was set up in 1900, and in 1907 it appointed a committee of linguists, scientists, and philosophers to judge the competing schemes⁵. In June 1907 the Delegation elected this committee according to its statutes, and in October of that year the members met in Paris, at the Collège de France, for eighteen long sessions^{2 • 6}. Wilhelm Ostwald, the Nobel-winning chemist, presided; Jan Baudouin de Courtenay and Otto Jespersen served as vice-presidents, and Louis Couturat and Léopold Leau as secretaries, with Louis de Beaufront added for his special competence².

The committee concluded that only two schemes deserved consideration: Zamenhof's Esperanto, unchanged since its launch in 1887, and Idiom Neutral, developed by the old Volapük Academy. Its decision was to accept Esperanto, but with major reforms along the lines of an anonymous project submitted under the pseudonym "Ido"⁵. In early 1908, after the Esperantist linguistic committee refused to apply these modifications, the Delegation named the new language "Ido" and published the first manuals and dictionaries². The Delegation dissolved on 31 July 1910, having founded Uniono por la Linguo Internaciona (ULI) to develop and propagate the language².

The anonymous author was soon unmasked as Louis de Beaufront, who had represented the international Esperanto organization before the committee; together with the French philosopher Louis Couturat and their colleagues, he set to work perfecting the scheme⁵. A critical account of the episode contends that the final choice was made by only four members of the Permanent Commission, Couturat, de Beaufront, Jespersen, and Leau, two of whom were secretly Ido's authors⁷.

Grammar and design reforms

Ido differs from Esperanto by greater closeness to the Romance languages in vocabulary and by special "logical" rules of word formation¹. The accusative ending, obligatory in Esperanto, is optional in Ido: it may mark an object when an unusual word order could create ambiguity, but it is not required in ordinary speech or writing^{1 • 8}. Adjectives do not agree with the nouns they qualify, adjectival agreement being eliminated entirely¹.

The orthography uses the Latin alphabet without any superscript diacritical marks, so text can be printed, typed, or transmitted without modification; there are no accented letters, and the alphabet matches English^{1 • 4}. Ido also introduced gender-neutral nouns with optional endings to indicate gender and a gender-neutral third-person pronoun lu, and it removed difficult consonant clusters such as ksc and kz³.

Word formation was the issue at the center of the Ido controversy. Ido imposes consistent rules on the endings that transform a word from one meaning or part of speech to another, simplifying the amount of vocabulary a learner must memorize⁹. Couturat, the author of Ido, took a prescriptive attitude toward word formation, while the partisans of Esperanto defended a descriptive stance; the controversy stimulated scholarly interest in planned languages and helped found the discipline of interlinguistics¹⁰. The CALS reference catalog lists about 14,000 roots in Ido's vocabulary¹¹.

Schism and decline

Publication of the Ido project split the Esperanto movement: a reform-minded wing of 10 to 20 percent supported Ido, while the rest remained loyal to Esperanto¹. ULI and an Academy of the language were established in 1909¹. The first half of the 1920s was a period of growth for the idist movement, which also underwent social renewal with the appearance of workers' idist organizations; international idist conferences were held regularly from 1921¹.

The movement then weakened from within. A drive for further reforms arose among idists, and carrying those reforms out deprived the language of stability and sharply reduced its number of adherents¹. Individual defections compounded the losses: Otto Jespersen, an early proponent, left the movement in 1929 to publish his own planned language, Novial¹². The idist movement was suspended during the Second World War and reactivated from the early 1950s, though on a much smaller scale¹.

Ido today

At the beginning of the 21st century Ido is represented by small groups in Great Britain, Spain, Italy, the Netherlands, Portugal, Russia, the United States, France, Germany, Switzerland, Sweden, and other countries¹. Fiction in the language, both original and translated, and works in various fields of knowledge exist, and lexicography has been thoroughly developed; the oldest journal, Progreso, has appeared since 1908¹.

Estimates of the speaking population run from 2,000 to 5,000 people, and no accurate statistics exist; online activity has increased interest in the language³. The community remains active in writing and conversation: Ido and Esperanto are similar enough to be nearly mutually intelligible in many situations, and Ido retains a continuous century-long written tradition alongside a small but living community⁸.

References

1. Идо, Большая российская энциклопедия (С. Н. Кузнецов), том 10, Москва 2008
2. Historique de la langue internationale Ido, Ido-France
3. Ido language, alphabet and pronunciation, Omniglot
4. Basic Grammar of the International Language Ido, idolinguo.org.uk
5. History of the International Language Ido, interlanguages.net
6. History of Our Language (Ido), by Prof. Otto Jespersen, 1912
7. The Truth about the Delegation in 1907, Ido-France archive
8. Ido, LinguaCommons
9. Ido language, Fact-Archive online dictionary
10. Klaus Schubert (2015), Word-Formation and Planned Languages, De Gruyter Mouton
11. CALS: Comparing Interlingua and Ido
12. An Elementary Grammar of Ido, Book Notices, Linguistic Society of America

Topic: Encyclopedia › Society and history › Languages and linguistics › Languages and dialects › Named languages by region › Named languages overview

Initially written Sep 17, 2026 · Reviewed: Oct 25, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 25, 2026

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