treaty
/ˈtrē-tē/
noun
an agreement or arrangement made by negotiation:
a contract in writing between two or more political authorities (such as states or sovereigns) formally signed by representatives duly authorized and usually ratified by the lawmaking authority of the state
private treaty
noun
any of numerous ports and inland cities in China, Japan, and Korea formerly open by treaty to foreign commerce
noun
a sale of property on terms determined by conference of the seller and buyer