The type of wave where matter moves at a right angle to the direction of the wave is called a transverse wave.

Here's a breakdown:

* Transverse wave: In a transverse wave, the particles of the medium oscillate perpendicular to the direction the wave travels. Think of a rope tied to a wall. If you shake the rope up and down, you create a wave that travels horizontally along the rope. The rope particles move up and down (perpendicular) while the wave itself travels horizontally.

* Examples of transverse waves: Light waves, electromagnetic waves, and waves on a string are all examples of transverse waves.

* Other types of waves: In contrast, in a longitudinal wave, the particles of the medium oscillate parallel to the direction of wave propagation. Think of a spring that you compress and release. The coils move back and forth (parallel) as the compression wave travels along the spring. Sound waves are a good example of longitudinal waves.