A diplomat is a person appointed by a state to conduct diplomacy with another state or international organization. The main functions of diplomats revolve around the representation and protection of the interests and nationals of the sending state, as well as the promotion of information and friendly relations.iktionary (0.00 / 0 votes) Rate this definition: diplomat (Noun). A person who is accredited, such as an ambassador, to officially represent a government in its relations with other governments or international organisations. diplomat (Noun).