The crossword solution for the term BE PERMANENT is WAVE. A wave is a disturbance that travels through space and time, transferring energy from one point to another. It is a fundamental phenomenon of nature, occurring in many different forms such as sound waves, light waves, and ocean waves. Waves are also used to describe the motion of particles in a medium, such as water or air. In physics, a wave is a type of oscillation that can be described mathematically.