visitor

(noun): Someone who visits someone else; someone staying as a guest.
(noun): Someone who pays a visit to a specific place or event; a sightseer or tourist.
(noun): (usually in the plural) Someone, or a team, that is playing away from home.
(noun): A person authorized to visit an institution to see that it is being managed properly.
(noun): An extraterrestrial being on Earth for any reason.
(noun): An object which lands or passes by Earth or its orbit.
(noun): A head or overseer of an institution such as a college (in which case, equivalent to the university's chancellor) or cathedral or hospital, who resolves disputes, gives ceremonial speeches, etc.
(noun): The object in the visitor pattern that performs an operation on the elements of a structure one by one.