an invented language, devised (1887) by Pol. physician L. L. Zamenhof (1859-1917), and proposed for use as an international (chiefly European) auxiliary language: it uses word bases common to the main European languages, and it has self-evident parts of speech (all nouns end in -o, all adjectives in -a, etc.), a single and regular conjugation of verbs, a few simplified inflections, etc.