Given that Esperanto is a very regular language, I would imagine that it would be easy to build morphological analysers and even syntactic parsers; parts-of-speech tagging is almost free due to the relevant markers -o/-a/-e/...

I have not come across any tools for natural language processing specifically for Esperanto, though. Is there just no interest in it?

  • If there aren't any, this would be a fun project to work on.
    – aweigold
    Aug 23, 2016 at 17:41
  • I agree! Years ago I started on a morphological analyser, but then didn't have time to complete it... But it looks so tempting! Aug 23, 2016 at 17:43
  • I think Google Translate uses morphological analysis to translate from/to Esperanto.
    – ForceBru
    Aug 23, 2016 at 17:53
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    Maybe you should clarify by saying what NLP stands for. Aug 23, 2016 at 18:55
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    Natural Language Processing -- I assumed that the combination with 'tools' would rule out the other common reading of 'Neurolinguistic Programming' Aug 23, 2016 at 18:56

3 Answers 3


There is some literature on using Esperanto (or other constructed or auxiliary languages, including some that are not intended for speaking) as a tool for translating between natural languages. One keyword for finding such works is interlingua (a technical term for such an intermediate language used in translations), although obviously this turns up primarily information about the naturalistic auxiliary language of the same name.

PS: The open source software Apertium can translate from Esperanto to English and from English, Spanish, French and Catalan to Esperanto. I tried translation from Esperanto to English, which turned out to be surprisingly good. (My Esperanto isn't good enough yet to judge the other direction.) I think with a bigger dictionary it would easily be better than Google's translator, and that's quite an achievement for a rule based translation system. It looks almost as if it should be feasible to develop software that accurately translates texts written in a controlled subset of Esperanto into every European language.

  • Yes, I was aware that Esperanto was a candidate for an interlingua in MT, though I have never actually come across a system that uses it. And its regularity was always given as a prime argument in favour of this application. Aug 23, 2016 at 20:30
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    This is probably the article you're looking for about using Esperanto as an intermediate language in machine translation: History and Heritage of the DLT (Distributed Language Translation) project Sep 19, 2016 at 1:43

About 10 years ago I found a software written in ruby which would extract prefixes, suffixes and roots from any esperanto word; I could not find it today. Still I remember the code was surprisingly short given the task, which made me think esperanto was the first "object-oriented" natural language. And makes me think that esperanto NLP software exist today. Here are two NLP articles on esperanto with respect to lexicography and teaching that may prove useful. I'm an intermediate esperanto speaker and a native French speaker; I find Google Translate and Apertum from French to Esperanto pretty good (better than some Google Translate translations from English to French). ĝis baldaŭ! Majol'


@aweigold (but not only) It would, really, be fun to work out an NLP model for Esperanto. If there are interested persons out there, even a GitHub project could be started. Presently, I am playing with an idea to create an Esperanto language model for spaCy (which does not exist, to my best knowledge). I still am a beginner with spaCy, though. And what about Toki Pona? :-)

@mayeulk The first link to Eckhard Bick's paper ('lexicography') is not valid any longer. To obtain the paper, you need to go to enter link description here, download the whole of the proceedings, and from the 'pdf' folder select paper_265.pdf. Anyway, thanks a lot for the indication.

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