Which component is referred to as the main structural unit of an aircraft?

The fuselage is referred to as the main structural unit of an aircraft because it provides the central structure that houses the crew, passengers, and cargo. It serves as the backbone of the aircraft, connecting and supporting other critical components such as the wings, tail, and landing gear. The fuselage is designed to withstand various stresses and aerodynamic forces during flight, playing a crucial role in maintaining the integrity and overall performance of the aircraft. Its design also contributes to the aircraft's aerodynamics, affecting lift and drag. Other components, while important for functionality, do not serve the same foundational and comprehensive structural role that the fuselage does.