·add. ·noun An artificial language, intended to be universal, devised by Dr. Zamenhof, a Russian, who adopted the pseudonym "Dr. Esperanto" in publishing his first pamphlet regarding it in 1887. The vocabulary is very largely based upon words common to the chief European languages, and sounds peculiar to any one language are eliminated. The spelling is phonetic, and the accent (stress) is always on the penult.