Esperanto is a constructed international auxiliary language.
Please see here.
dictionaries/esp-eng.txt
Dictionary Esperanto - English
This dictionary can be used by the software ding.
dictionaries/esp-deut.txt
Wörterbuich Esperanto - Deutsch
Dieses Wörterbuch kann mit der Software ding verwendet werden.
I think there are several levels of artificial languages. These levels depend on the number of active speakers, the level of speakers, the number of good teachers and the number of good texts.
The language is unknown. Perhaps few people discuss this language. A meaningful application of this language is not possible. There are no good teachers and nobody writes good texts. Most artificial languages are at this level.
Hundreds to thousands of lay people discuss the correct application of this language. However, a meaningful application of this language is not possible. There are no good teachers and nobody writes good texts. An example of this level is the “language” Toki Pona.
Thousands of amateurs discuss the benefits of this language. Organizations are formed to spread the language. But these organizations are concerned with themselves. The reason is: there are not enough good teachers and there is no strategy to spread the language. There are some good texts, but that is not enough. The number of good speakers is insufficient. People talk about this language, but not in this language. Conversations about everyday topics are not common. Interlingua has this level.
Hundreds of thousands of people speak this language. People also talk about everyday topics. There are many organizations that want to spread this language. The number of good texts and good teachers is increasing. The language has a long tradition. I think only Esperanto has this level.
The language has become a normal language. There are enough good texts and good teachers. The organizations that spread this language are becoming redundant. You can find enough partners to practice this language. Dialects of this language are emerging. You can use this language in hotels and airports in at least one country. I don’t think an artificial language could ever reach this level.