(n) :
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. Example: "The U.S. dollar is the Esperanto of currency."