* Wavelength (λ): The distance between two consecutive crests (or troughs) of a wave.

* Amplitude (A): The maximum displacement of a wave from its equilibrium position.

* Wavefront: The line or surface that connects all points on a wave that are in phase (i.e., have the same displacement and velocity). This isn't strictly a distance, but it represents a spatial location along the wave.

Let me know if you'd like more detail on any of these!