What is meant by terminal velocity?

Essentially that objects have a top speed falling through air to the ground, which is called terminal velocity. This is because we are surrounded by air, so when moving, objects have to push past the air particles to get where they're going. The faster an object moves, the more air particles it has to push past per second, so the object has to accelerate more mass per second. If you remember, Newton's second law states that F = ma, where F is the net force, m is the mass being acted on and a is the acceleration of that mass. Therefore the object exerts more force on the air the faster it moves and because every action has an equal and opposite reaction (Newton's third law), the air exerts more force on the object the faster the object moves. This force from the air is the drag or air resistance you're probably familiar with.Anyway, when an object starts falling, the only force acting on it is its weight (as it has no velocity to begin with), so it accelerates towards the ground. As it speeds up, the drag force on it increases as just discussed. This then reduces the overall downwards force on the object as the drag cancels out some of the weight force. So the object's acceleration decreases. Eventually, the object will be falling fast enough that the drag force will be equal and opposite to the weight force, so the two forces will balance and there will be no net, or resultant force. As a result, the object will stop accelerating and will stay at a maximum speed, called its terminal velocity. Remember that the object is still very much moving, it just has a constant speed. Objects don't stop mid-air when falling after all do they? Does that help answer your question?