Definitions

A State (or regional economic integration organization, such as the European Union) that has ratified, acceded to, or otherwise formally indicated its intent to be bound by an international agreement, and for which the agreement is in force. While most Parties have signed the instrument in question, it is not usually a necessary step in order to become a Party. (Source: InforMEA)

Hierarchy
Alternative labels:
contracting party
member state
participant
signatory