For an Italian word, ‘ciao’ appears to belong to no one and to everybody all at once. It has been adopted by at least 38 languages, and its impact extends well beyond Europe, Japan, and Latin America, people part ways warmly on the crest of this single syllable, and while not technically English, you will be greatly understood (if not considered a little impacted) if you use it in the US. Even if Italy lays claim to the origin of ciao, it has long since transformed into a cosmopolitan touchstone — a word that will register simply about anywhere.