What is the definition of a pendentive in architecture?

The definition of a pendentive in architecture refers to a curved triangle of vaulting that is created at the intersection of a dome with its supporting arches. This architectural feature is crucial for transitions between the circular base of the dome and the square space below it, allowing for a seamless and structurally sound integration.

Pendentives effectively enable the dome to be placed over a square room, which would otherwise be difficult to achieve without a method to bridge the differing shapes. Their unique geometry not only supports the weight of the dome but also distributes it evenly to the arches below, enhancing the overall stability of the structure. This is particularly significant in grand architectural works, such as Byzantine churches, where the use of pendentives facilitated the creation of large, open interiors topped with impressive domes.

The remaining choices do describe elements related to domical architecture or construction techniques, but they do not accurately encapsulate the specific structural role of pendentives. The first option most precisely defines what a pendentive is and its architectural significance.