After a guest has checked out, they are no longer considered "check-in" or "check-out" but rather "guest who has already departed." This phrase is commonly used in hotel management systems, customer service communications, and inventory management to indicate that the room is available for new reservations. For example, when a hotel staff member is checking the availability of rooms, they might see a note like "Guest has already departed" next to a room number. This signifies that the room is free and can be booked by another guest.