Contract

An agreement, upon sufficient consideration, to do or not to do a particular thing. A covenant or agreement between two or more persons, with a lawful consideration or cause. A deliberate engagement between competent parties, upon a legal consideration, to do or abstain from doing, some act. A contract or agreement is either where a promise is made on one side and assented to on the other; or where two or more persons enter into engagement with each other by a promise on either side. A contract is an agreement by which one person obligates himself to another to give, to do. or permit, or not to do something expressed or implied by such agreement.
https://thelawdictionary.org/contract/