What is another word for speed that ends with city?

You are probably thinking of the word "velocity" but they are not the same thing.

Speed is a measure of the distance traveled in a unit of time. 50 miles per hour, for example represents a speed. It says nothing about the direction of travel.

Velocity is also a measure of speed but it also has a direction. 50 miles per hour towards the West is a velocity. So is 50 miles per hour toward the East but they are different values.

Velocity is used when the direction of motion is important. A ball that has been thrown into the air can be traveling at 5 meters per second. Knowing the speed tells us nothing about whether it is going up or on its way back down again. A velocity that refers to upwards as positive will tell us. + 5 meters per second and the ball is going up. - 5 meters per second tells us that the ball is falling towards the ground.