A visitor was a person who spent a short interval of time at a particular location. Visitors could come for social, business, or professional reasons, or for sightseeing and tours.
The Vulcan monastery at P'Jem had a reliquary in its catacombs. According to the Vulcan elder, no visitors were allowed at the reliquary – this would be blasphemy. Only members of the high order were allowed inside. (ENT: "The Andorian Incident")