Definition: The word "accelerate" means to increase speed or speed up; it involves a change in direction, velocity, or rate of movement. In Greek mythology, a character named Aesculapius was known for his speed and agility, who was able to accelerate to great speeds by riding a horse called the Argo. He often helped other animals and plants by accelerating them. So, "accelerate" is a verb that means to increase or raise something's speed or velocity; it involves changing its direction, velocity, or rate of movement.