pendentive
/pɛnˈdɛntɪv/
noun
- A curved triangular piece of masonry that fills the space between a dome and the square or rectangular base it rests on, allowing the dome to be supported above a room with walls at right angles.
- In Byzantine churches, pendentives allowed builders to place large domes over rectangular rooms.
- The pendentives in the cathedral were decorated with beautiful mosaics of saints.
- The architect used four pendentives to transition from the square base to the circular dome.