It is called that because you volley the ball back and forth.
How Did Volleyball Get Its Name?
Because you are volleying a ball over a net.
1st, your using a ball (vollleyball) 2nd. You volley a ball back and forth acroos a net. (volleyball)
In 1896, Alfred Halstead noticed the volleying nature of the game that he was watching at the International YMCA Training School (Springfield College). It became volley ball with two words. Then later became known as volleyball.