The Encyclopaedia Britannica defines treaty as:
Contract or other written instrument binding two or more states under international law. The term is generally reserved for the more important international agreements, usually requiring, in addition to the signatures of authorized persons, ratification by the governments involved. A treaty may be bilateral or multilateral; it usually contains a preamble, an enumeration of the issues agreed on, and clauses that discuss its ratification procedures, lifespan, and terms for termination. Treaties may be political, commercial, constitutional, or administrative, or they may relate to criminal and civil justice or codify international law."
Encyclopaedia Britannica (online at 6 February 2023) ‘treaty summary’