Cast means how far a bow will shoot an arrow. It was commonly used before there were inexpensive devices that could easily measure velocity.
Initial arrow velocity and cast are different in several meaningful respects. Let's say that we have bow A that will shoot a 400 grain arrow at 190 fps, and bow B that will shoot a 500 grain arrow at 180 fps. Bow B might have a greater cast than bow A, because the increased momentum of the arrow shot by bow B will overcome air resistance better than the arrow shot by bow A, even though bow B has a lower initial arrow velocity than bow A. Bow A might have a flatter trajectory than bow B out to 30 yards, but bow B might have a flatter trajectory than bow A at 80 yards.