The word "accelerating" describes an increase in speed, but its antonyms show a variety of ways to describe a decrease in speed or a lack of motion. The opposite of "most accelerating" can be described as decelerating, slowing down, reducing speed, or even coming to a complete stop. Other antonyms include decelerative, sluggish, lethargic, stagnant, and stationary. The context in which the term is used may determine which of these options best fits its antonym. For instance, in the context of a car, decelerating would be the most fitting antonym, whereas in the context of a person, sluggish may be a more appropriate antonym.