The term 'DESIGNED FOR FLYING' can be summarized by the crossword solution AERO, which stands for aeronautics. Aeronautics is the science of designing and building aircraft, as well as operating them in the air. It is a branch of engineering that deals with the study of the motion of air and the forces that act on an aircraft. AERO is used to describe anything related to the science of aeronautics, such as aircraft, engines, and other components.