(1) An artificial language based as far as possible on words common to all the European languages
From , from , from . Originally, this was the pseudonym assumed by the language's creator, L. L. Zamenhof, and the language was called .
- The name of an international auxiliary language designed by L. L. Zamenhof with a base vocabulary inspired by Indo-European languages such as English, French, German, Italian, Spanish, and Russian, and having a streamlined grammar with completely regular conjugations, declensions, and inflections.
- (metaphorical) Anything that is used as a single international medium in place of plural distinct national media.
- The U.S. dollar is the Esperanto of currency.