Free Fall 

A free falling object is an object that is falling under the sole influence of gravity. Any object that is being acted upon only by the force of gravity is said to be in a state of free fall. There are two important motion characteristics that are true of free-falling objects:

Free-falling objects do not encounter air resistance.

All free-falling objects (on Earth) accelerate downwards at a rate of 9.8 m/s/s (often approximated as 10 m/s/s for back-of-the-envelope calculations)

 Definition Provided by Physics Classroom

 Now throw a ball up, it velocity is positive because it is moving up, but is being pulled down. So the ball has a positive velocity and a negative acceleration, describe the motion of the ball.  Well the ball continues to move up, but is slowing down as it keeps going higher and higher in the air.  When the ball gets to the maximum height the ball stops briefly, describe the motion of the ball.  Well ball isn't moving so the balls positive velocity has "drained" away until it goes to zero, is still being pulled?  in which direction is it being pulled?  It is still being pulled by gravity, and gravity is still pulls down, so it's still accelerating at -9.8 m/s/s.  Now the ball starts falling back to the Earth, it velocity is negative because its moving down, it the pull of gravity still down?  is the acceleration still down?  Yes gravity is still pulling down, and so the acceleration is still -9.8 m/s/s (still down).  Describe the motion of the ball.  The ball continues to move down but it gets faster and faster as it falls towards the earth, negative acceleration, negative velocity and the ball speeds up (in the downward direction).

So is this what you would call Deceleration?  

The slowing down of an objects SPEED is called braking, not deceleration.