How do you spell visitor in french?

Much depends on the kind of visitor. A tourist would be un touriste A social visit to your house would be un invite ( une invitee if female ). This means, literally, someone who was invited, but it is used for visitors whether or not you actually asked them to come. Someone who turns up to perform some function would be known by the name of the function. e.g. the mailman =le facteur ; the plumber =le plombier; a door-to-door salesman = un colporteur.