Which term describes a flight pairing that returns to the base on the same day without an overnight stay?

The term that describes a flight pairing returning to the base on the same day without an overnight stay is "Turn." A turn involves a flight that is completed within the same day, allowing crew members to return home without the need for lodging. This type of schedule is common in the airline industry for maximizing efficiency and minimizing costs, as it ensures that flight attendants can work a full day without needing to remain away from their home base.

The other options refer to different types of flight pairings. For instance, a "Two Day" pairing typically involves two work days with an overnight stay, while a "Three Day" pairing includes three work days, often with multiple overnights. "Overnight" itself simply refers to any flight or pairing that requires the crew to stay overnight away from their base, which does not fit the description of returning home the same day.