Which term describes a circular opening at the top of a dome?

Which term describes a circular opening at the top of a dome?

• A. Oculus
• B. Lunette
• C. Pantograph
• D. Orthogonals

Answer: (A)

The circular opening at the top of a dome is called an oculus. The word comes from Latin for “eye,” highlighting its function as a light-filled opening that also lightens the structure. A classic example is the Pantheon’s dome, where the oculus is the only source of daylight. A lunette is a curved, often semicircular window or decorative niche, not a full circular opening at the dome’s apex. Pantograph refers to a copying-mechanism device, and orthogonals are the straight lines used in perspective drawing. So the best term for that dome opening is oculus.

The circular opening at the top of a dome is called an oculus. The word comes from Latin for “eye,” highlighting its function as a light-filled opening that also lightens the structure. A classic example is the Pantheon’s dome, where the oculus is the only source of daylight. A lunette is a curved, often semicircular window or decorative niche, not a full circular opening at the dome’s apex. Pantograph refers to a copying-mechanism device, and orthogonals are the straight lines used in perspective drawing. So the best term for that dome opening is oculus.