celerity

noun4

1. •
   Speed, swiftness.

   • O most kind maid, / It was the swift celerity of his death, / Which I did think with slower foot came on, / That brain'd my purpose. — 1603
2. •
   The speed of an individual wave (as opposed to the speed of groups of waves); often denoted c.
3. •
   The speed with which a perturbation to the flow propagates through the flow domain.
4. •
   (old-fashioned) The speed of symbol transmission, now called baud rate.

   • ...and many endeavours have been made, not only to transmit signals with celerity, but also to transmit more than one communication at the same time along the same wire. — 1885