Source : Webster's Revised Unabridged Dictionary (1913)

Esperanto \Es`pe*ran"to\, n.
   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. --
   {Es`pe*ran"tist}, n.

Source : WordNet®

Esperanto
     n : an artificial language based as far as possible on words
         common to all the European languages