What is the term for a small dome commonly used in architecture?

The term for a small dome commonly used in architecture is indeed "cupola." A cupola is typically a small, dome-like structure that crowns a building, often serving both decorative and functional purposes. It can be found atop various types of buildings, including churches, government buildings, and even homes. The architectural design allows it to provide a space for ventilation, natural light, or a viewing platform, in addition to enhancing the aesthetic appeal of the structure.

Understanding the context of the other terms helps clarify why "cupola" is the correct choice. A pendentive is an architectural feature that allows for the circular base of a dome to be placed over a square room, but it doesn't refer to a standalone dome itself. An amphora is a type of ancient Greek pottery used for storage, typically not related to architectural elements. Raku refers to a specific style of Japanese pottery that involves a particular firing technique and is unrelated to architectural domes. Thus, the definition and context regarding cupolas clearly distinguish it as the accurate term in this instance.