Janitor n. : A door-keeper; a porter; one who has the care of a public building, or a building occupied for offices, suites of rooms, etc.

Example:
What is the best prank to pull on a Janitor?

Taxonomy
Janitor, free encyclopedia, tasks, custodian, technician, building superintendent, contractor, employs, cleaners, search, character, Unsourced, takes care, managerial duties, receive training, employer, job, housekeepers.

Defination from the web:
janitor or custodian (called caretaker in British English, see American and British English differences) is a person who takes care of a ... Janitors are responsible primarily for cleaning, and often (though not always) some maintenance and security. ...