An appointment is a time reserved for something such as a doctor visit, much like a reservation.
An appointment, in government also refers to the assignment of a person by an official to perform a duty, such as a presidential appointment of a judge to a court. This may also happen for an office which is normally elected, but has an unexpected vacancy. A person appointed but not yet in office is a designate.
The power of appointment, in law, is the ability of a testator to select another person to dispose of the testator's property.
An appointment of clergy, in Christianity, is made by a bishop to a particular ministry setting, particularly in denominations which practice episcopal forms of church government and polity (such as Anglicanism and United Methodist Church.) Typically, a pastor is appointed to a particular church or parish.
Appointment is used to describe a system of selecting candidates in which the choice is made by an individual or panel rather than by a poll of the populace in general (election), or through random selection (allotment/sortition) as used to select juries.
