The term "semi-rigid" refers to materials or structures that possess a combination of flexibility and stiffness. These materials can bend or deform under pressure but will return to their original shape when the pressure is removed. This property makes them useful in various applications, such as in the design of certain types of packaging or in the construction of lightweight structures. In engineering, semi-rigid connections are often used in frameworks, allowing for some movement while still providing support. This balance between rigidity and flexibility can enhance the overall performance and durability of structures, making them suitable for dynamic environments, such as those found in bridges or buildings.