Answer: esperanto

AnswerCrossword Clue
ESPERANTO"Saluton! Kiel vi fartas?," e.g.
ESPERANTOLanguage in which plural adjectives end in -aj
ESPERANTO"I love you" is "Mi amas vin" in it
ESPERANTO"Please" and "thank you" are "bonvolu" and "dankon" in it
ESPERANTOLanguage with no irregular verbs
ESPERANTOLanguage devised in 1887
ESPERANTOOne prates oddly in a language few can understand (9)
ESPERANTOIt has just 16 rules of grammar
ESPERANTOThe 1965 William Shatner film "Incubus" is in it
ESPERANTOLanguage in which plurals are formed by adding -oj
ESPERANTOPerson ate boiled tongue (9)
ESPERANTOLingua franca, for some
ESPERANTOStalin called it "the language of spies"
ESPERANTOL.L. Zamenhof's creation
ESPERANTOInternational language.
ESPERANTOArtificial language.
ESPERANTOOdd language.
ESPERANTOUniversal language.
ESPERANTOIt means "one who hopes"
ESPERANTOYou'll find it in 180,000+ Wikipedia articles
ESPERANTOProfessor Zamenhof's invention
ESPERANTOArtificial language
ESPERANTOStalin's "language of spies"