What characteristic defines a hip roof?

A hip roof is defined by its sloping sides that come together at the top to form a ridge, without any gable ends. This design ensures that all sides of the roof slope down toward the walls, which provides structural stability and allows for better rain and snow runoff. The absence of gables contributes to the roof's aerodynamic shape, which can be favorable in areas prone to high winds.

In contrast, steep vertical angles are often found in other types of roofs, such as gable roofs or certain architectural styles, but do not specifically characterize a hip roof. A flat surface does not describe a hip roof since it is defined by its slopes. Similarly, having multiple gables pertains to roof types with distinct peaks and vertical sections, which is not a feature of hip roofs as they lack the vertical faces that characterize gables. Therefore, the defining characteristic of a hip roof is indeed its sloped sides without gables.