What is bid adieu?

Bid adieu is a phrase that is commonly used to say goodbye or farewell in a formal or polite manner. It is derived from the French language where "adieu" means farewell. It is typically used in situations where one is expected to show respect or formality, such as in a professional setting or when parting with someone who holds a higher social status. The phrase is often accompanied by a gesture of respect such as a bow, nod, or handshake. Additionally, it is also used to signify the end of something, such as the closing of a chapter or the end of an event.