What is the name of the ball on the top of a flagpole?

The term used to describe the ball or ornament located at the top of a flagpole is known as a truck. This component serves both decorative and functional purposes, as it often holds the flag in a manner that allows it to be flown freely and correctly without hindrance. The truck might be designed to accommodate a halyard or rigging, which is essential for raising and lowering the flag.

The other choices do not accurately describe this specific element of a flagpole. A cap typically refers to a covering or protective piece that may be found on various structures but is not the recognized term for the ball atop a flagpole. A sphere is a geometric shape that does not convey the specific context of flagpoles, while a post generally refers to the vertical structure itself and not the ornamentation at its peak. Thus, truck is the most appropriate term for this feature of a flagpole.