Diagram of a sunken courtyard in a villa

Quick answer：

A sunken courtyard in a villa refers to a garden or courtyard area that is lower in elevation compared to the surrounding ground level. This design feature can create a sense of privacy, seclusion, and a unique visual contrast. Sunken courtyards are often used in architectural design to enhance the aesthetics and functionality of a villa. They can be decorated with various elements like water features, landscaping, or decorative structures to create a tranquil and inviting space.