Which definition correctly describes a 'seaplane'?

A seaplane is defined as a powered aircraft that is specifically designed to land on water. This capability allows it to operate from aquatic environments, making it distinct from traditional aircraft that require runways for takeoffs and landings. The design of a seaplane typically includes features such as floats or a hull that allow it to glide smoothly on the surface of the water and take off or land without the need for paved airstrips.

This definition emphasizes both the function of the aircraft and its adaptability to water surfaces, which is integral to its classification. Understanding this can help in distinguishing seaplanes from other types of aircraft and vessels, as they are uniquely suited for operations over water, while other options describe different types of aviation or marine vehicles that do not align with this specific purpose.