CONTRACT, in a general sense, a mutual consent of two or more parties, who voluntarily promise and oblige themselves to do something; pay a certain sum, or the like. All donations, exchanges, leases, &c. are so many different contracts.
CONTRACT is particularly used, in common law, for an agreement or covenant between two, with a lawful consideration or cause. As, if I sell my horse for money; or covenant, in consideration of 20l. to make you a lease of a farm; these are good contracts, because there is quid pro quo.