There's no need for the "/s" on the end, there. Deceleration, and especially in this case with a natural frame of reference, deceleration is negative acceleration.
The magnitude of the velocity vector is dependent on the frame of reference.
If you measure the same object's velocity from a spaceship traveling through the solar system, you'll get a different answer from what we measure from Earth.
That's why physics doesn't distinguish between acceleration and deceleration. What looks like acceleration in one frame looks like deceleration in a different frame.