2. A reference to being tactful and skillful when dealing with people: While growing up, Jill learned that being diplomatic with her parents was quite effective in getting what she wanted, instead of her yelling and behaving badly!
Diplomatic applies to social behavior which is as sensitive as an ambassador's and so it applies to having social behavior that is smooth and courteous.
2. A bag in which official correspondence travels between a government office and an embassy of that government in another country, carried by a special messenger: The diplomatic bag is not subject to the same regulations that govern ordinary mail.
An official courier is also immune from detention or arrest, and he or she has the diplomatic bag under his protection and conveys it from one legal institution to another such authorized location of the same rulership in a different nation.