Which term is not part of a masonry arch?

• A. Quantum
• B. Voussoir
• C. Keystone
• D. Abutment

Answer: (A)

Understanding the terms used for a masonry arch is about recognizing which pieces work together to carry and transfer weight. In a traditional masonry arch, the individual wedge-shaped blocks that make up the curved form are called voussoirs. They are arranged so that each block transfers thrust to its neighbors, directing the load toward the supports. The central top block that locks the arch is the keystone, which helps the arch act as a single continuous ring. At each end, abutments provide resistance to the horizontal thrust produced by the arch, keeping the structure stable.

The term quantum does not belong to masonry arch vocabulary; it comes from physics and refers to a discrete amount of something, such as energy, and has no function in describing arch components. So the term that is not part of a masonry arch is quantum.