What does the term 'trough' refer to in wave terminology?

In wave terminology, the term 'trough' specifically refers to the lowest part of a wave. This is the point on the wave where the displacement from the rest position is at its minimum, making it the opposite of the crest, which represents the highest point of the wave. Understanding wave structure is important in various fields such as physics and engineering, especially when analyzing wave behavior in mediums such as water, sound, and electromagnetic waves. Knowing that the trough signifies low displacement helps in visualizing how waves propagate and interact with other waves or obstacles. The other terms in the question pertain to different aspects of wave characteristics: the peak refers to the highest point, distance between waves relates to wavelength, and the speed involves how fast the wave travels rather than its vertical position.