janitor (n.)

1580s, "an usher in a school," later "doorkeeper" (1620s), from Latin ianitor "doorkeeper, porter," from ianua "door, entrance, gate," from ianus "arched passageway, arcade" (see Janus) + agent suffix -tor. Meaning "caretaker of a building, man employed to see that rooms are kept clean and in order" first recorded 1708. Fem. forms were janitress (1806), janitrix (1818).