from The American Heritage® Dictionary of the English Language, 4th Edition
- interj. Used to express farewell and good wishes to a departing traveler.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- interj. Used to wish someone a good journey.
from The Century Dictionary and Cyclopedia
- n. A parting salutation meaning, I wish you ‘a pleasant journey’ (or ‘voyage’ if by water).
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an organized expression of goodwill at the start of a trip or new venture
French : bon, good + voyage, journey.(American Heritage® Dictionary of the English Language, Fourth Edition)
Whole phrase borrowed from French: bon ("good") + voyage ("journey"). (Wiktionary)