Plain English Meaning
It is the final set of checks the pilot runs through after taxiing out and before lining up to take off, making sure the airplane and its systems are ready to fly safely.
Full Definition
A written list of items the pilot completes after taxiing to the runup area and before entering the runway for takeoff. It confirms that the engine, flight controls, instruments, fuel system, trim, flaps, and other systems are properly set and functioning, and that the airplane is configured and ready for the takeoff roll.
Context Anchor
Used on the ground near the runway, after taxiing and before starting the takeoff roll.