Which term describes a long, funnel-shaped cloud that extends to the ground?

The term that describes a long, funnel-shaped cloud that extends to the ground is "tornado." Tornadoes are characterized by their funnel shape, forming from severe thunderstorms, particularly supercell thunderstorms, and are capable of causing significant damage due to their high rotational winds.

Unlike a hurricane or a cyclone, which are large weather systems characterized by strong winds and heavy rain but do not have the specific funnel shape associated with tornadoes, a tornado is distinctly identified by its narrow, rotating column of air that touches both the cloud base and the Earth's surface. A waterspout is a type of tornado that occurs over water, but it isn't the broad term that encompasses all ground-touching funnel clouds. Hence, "tornado" is the most accurate description for the phenomenon in question.