The material that travels through mechanical waves is called the medium.

Here's a breakdown:

* Mechanical waves are disturbances that travel through a medium.

* Medium is the substance that the wave travels through. It can be a solid, liquid, or gas.

Examples:

* Sound waves travel through air, water, or solids.

* Seismic waves travel through the Earth's crust.

* Waves on a string travel through the string itself.

Key point: Mechanical waves require a medium to travel. They cannot exist in a vacuum.