The term that refers to the speed at which a falling object stops accelerating and begins to fall at a constant rate is terminal velocity.

Here's why:

* Acceleration due to gravity: When an object falls, it accelerates due to the force of gravity.

* Air resistance: As the object falls faster, it encounters increasing air resistance. Air resistance acts as an opposing force to gravity.

* Terminal velocity: Eventually, the force of air resistance becomes equal to the force of gravity. At this point, the net force on the object is zero, and it stops accelerating. The object continues to fall at a constant speed, which is called terminal velocity.

Let me know if you'd like to know more about terminal velocity!