What is the movement of a water particle in a wave called?

If the particle moves up and down it would be called amplitude.

The movement of a water particle in a wave is called orbital motion. When a wave passes through water, the water particles move in an orbital motion, which means they move in a circular or elliptical path. This orbital motion is primarily in a vertical direction, although there can also be some horizontal movement depending on the type of wave.

To understand the orbital motion of water particles in a wave, you can imagine a particle on the surface of the water. As the wave passes, the particle moves up and down in a circular or elliptical path. This motion transfers energy through the water and causes the wave to propagate.

It's important to note that although the water particles themselves move in an orbital motion, the overall direction of wave propagation is different. The wave energy, while it spreads out through the water, travels in a horizontal direction, perpendicular to the individual particle motions.

So, in summary, the movement of a water particle in a wave is called orbital motion, where the water particles move in a circular or elliptical path as the wave passes through.