When describing the motion of waves, wave speed refers to how fast a specific point on the wave, such as a crest or trough, travels through the medium.

Here's why:

* Waves don't transport matter: Waves transfer energy, not matter. Think of a wave in the ocean; water molecules oscillate up and down, but they don't travel long distances.

* The wave pattern moves: What moves is the pattern of the wave, the shape formed by the oscillations. The speed of this pattern is the wave speed.

To summarize, wave speed is the speed at which a wave's disturbance propagates through a medium.