The maximum displacement on either side of the equilibrium position in a wave is called the amplitude.

Here's a breakdown:

* Equilibrium Position: This is the resting position of the medium or particle before the wave passes through.

* Displacement: The distance a particle in the medium moves from its equilibrium position due to the wave.

* Amplitude: The maximum displacement from the equilibrium position. It's essentially the "height" of the wave.

So, the amplitude represents the intensity or strength of the wave. A wave with a larger amplitude has a greater maximum displacement and carries more energy.