What is the bottom part of a wave called?

The bottom part of a wave is known as the trough. This refers to the point where the wave reaches its lowest position in relation to the equilibrium level. In the context of wave behavior, such as in water waves, the trough is crucial for understanding the wave's characteristics. It represents the area where energy is at its minimum, and it helps in calculating other wave properties like wavelength and amplitude.

Understanding wave terminology is important, as the crest, which refers to the highest point of a wave, provides contrast to the trough. While the peak and valley are terms that might describe similar concepts, they do not specifically align with the terminology used in wave physics. The defined roles of crest and trough, therefore, are essential in the study of waves and oscillations in various physical contexts.