convention

noun | con·ven·tion

1. : an agreement between nations for regulation of matters affecting all of them

2. : an agreement enforceable in law : contract

3. : an assembly of persons met for a common purpose; especially : a meeting of the delegates of a political party for the purpose of formulating a platform and selecting candidates for office : a meeting of the delegates of a political party for the purpose of formulating a platform and selecting candidates for office