What does the term 'deceleration' mean?

Deceleration refers to the process of slowing down. In physics, deceleration is the decrease in velocity of an object over time. When an object is decelerating, it experiences a negative acceleration, which means that its speed is reducing. This concept is essential in understanding motion, as it contrasts with acceleration, where an object is increasing its speed. While stopping suddenly can be a form of deceleration, it's more accurate to define deceleration itself as a broader term that simply involves a reduction in speed rather than a complete stop. This is why the answer that defines deceleration as slowing down is the most fitting explanation.