rapidity

The state or property of being rapid; celerity of motion or action; quickness of performance or execution; fast rate of progress or advance.

Synonyms Speed, Swiftness, etc. (see quickness), haste, expedition, despatch.

The quality or state of being rapid; swiftness; celerity; velocity.

speed, swiftness; the condition of being rapid

A measure of velocity relative to the speed of light

A measure of the velocity of a particle in a beam relative to the beam#s axis

a rate that is rapid