A force that is opposite to the direction of motion is called friction.

Here's why:

* Friction is a force that opposes the relative motion of two surfaces in contact. This opposition means it acts in the opposite direction of the intended movement.

* Examples:

* Pushing a heavy box across the floor - friction between the box and the floor slows the box down.

* A car braking - friction between the brake pads and the rotors converts kinetic energy into heat, slowing the car down.

Let me know if you'd like more information about friction!