What defines a 'field' in interlaced video?

In interlaced video, a 'field' refers specifically to one half of a complete frame. This concept is integral to how interlaced video works, as it enhances the efficiency of video playback. Each field comprises either the odd-numbered lines or the even-numbered lines from the frame. By alternating between these fields, interlacing improves the illusion of motion and can reduce flicker, creating the perception of a smoother image without requiring the full frame to be displayed at once.

Understanding this definition is crucial in fields such as broadcasting and video production, where the technical approach to how images are displayed can impact viewer experience significantly. The other options do not accurately describe the characteristics of a field in interlaced video, which is why they do not serve as correct definitions.