If the object gets slower, and the speed decreases, it is called deceleration, or negative acceleration.

Why say negative acceleration when deceleration makes it so much clearer?

Consider a vehicle that at first is moving forward at a great velocity, but with a negative acceleration.

In this case, negative acceleration would indicate that .

In science a "deceleration" is called a "negative acceleration", for example: 2 m/s.

This is a negative acceleration a in the line of travel.

It was 'X', and enough negative acceleration was applied to make an easy landing possible.

But it is getting a negative acceleration from gravity.

"That's it, all x," he announced, after completing his calculations, and reduced their negative acceleration by a third.

It can be thought of as negative acceleration.