Bon voyage is a cheerful French expression used to bid farewell and wish someone a safe journey. The antonyms or opposite words for bon voyage could typically be phrases conveying sadness or discouragement, such as "good riddance," "farewell forever," or "pleasant journey." These phrases convey a sense of negativity and a lack of sincere wishes for a successful and safe journey. However, it is always wise to bid someone a kind and genuine goodbye, wishing them well in their travels, no matter the circumstances of their departure. After all, a friendly and positive goodbye can make a significant difference in someone's journey, no matter how long or short.