Diplomacy Jargon

Accession
The procedure by which a nation becomes a party to an agreement already in force between other nations
Accords
International agreements originally thought to be for lesser subjects than covered by treaties , but now really treaties by a different name.
Ad Referendum
An agreement reached ad referendum means an agreement reached by negotiators at the table, subject to the subsequent concurrence of their governments.
Agrément
Diplomatic courtesy requires that before a state appoints a new chief of diplomatic mission to represent it in another state, it must be first ascertained whether the proposed appointee is acceptable to the receiving state. The acquiescence of the receiving state is signified by its granting its agrément to the appointment. It is unusual for an agrément to be refused, but it occasionally happens.
Attaché
Civilian attachés are either junior officers in an embassy or, if more senior, officers who have a professional specialization such as “labor attaché”, “commercial attaché”, “cultural attaché”, etc. On the military side, an embassy will generally have either an army attaché, naval attaché, or air attaché – and often all three. In American embassies, the senior of the three is called the defense attaché and is in charge of all military attaché activities. These consist largely of liaison work with local military authorities and of keeping informed on host country order of battle.
Belligerency
A state of belligerency is a state of armed conflict. Belligerents are direct participants in the conflict.
Casus Belli
An action by one state regarded as so contrary to the interests of another state as to be considered by that second state as a cause for war.
Communiqué
A brief public summary statement issued following important bilateral or multilateral meetings. These tend to be bland and full of stock phrases such as “full and frank discussions”, and the like. Occasionally, getting an agreement on the communiqué turns out to be the most difficult part of the meeting.
Diplomatic Corps
The body of foreign diplomats assembled at a nation’s capital. In cities where consuls and consul general are resident, the are collectively known as the consular corps. The dean of both corps is usually that official who had been at his post the longest. There are exceptions to this later rule, however. For example, in some Catholic countries, the papal nuncio is always the dean. The dean represents the corps in collective dealings with host country officials on matters of a ceremonial or administrative character affecting the corps as a whole.
Diplomatic Immunity
Exemption of foreign diplomatic agents or representatives from local jurisdiction. Also see Diplomatic Immunity.
Diplomatic Note
A formal written means of communication among embassies.
Persona Non Grata
An individual who is unacceptable to or unwelcome by the host government.
Rapporteur
The official of a committee or subcommittee whose job is to prepare a summary report of its discussions and conclusions.
Rapprochment
The establishment of improved relations.
Ratification
The act, subsequent to a treaty’s having been negotiated, by which a government commits itself to adhere to that treaty. In the United States, it is inaccurate to speak of the Senate’s ratifying a treaty. The executive does this, but only after the Senate has given its consent.
Recognition
Commonly used in connection with the recognition by one state of 1) the existence of another state (for example when a new one is formed), or 2) the existence of a government which is in effective control of a state. The term “de facto recognition” means recognition that a state, or a government of a state, in fact exists – but it also means the withholding of full official recognition of this. When the latter is extended, it is termed “de jure recognition”. It is a distinction based more on diplomatic convenience than on logic.