Meaning

noun a written agreement between two states or sovereigns

originThe noun is derived from Middle English trete, trety (“bargaining, negotiation; discussion; conference, meeting; entreaty, persuasion; agreement, contract, covenant; arrangement, settlement; agreement between two rulers, states, etc.; written work on a particular subject, treatise; subdivision of a written work, section”) [and other forms], from Anglo-Norman treté, traité, treaté, and Old French…

Etymology from Wiktionary, CC BY-SA 3.0