Difference between speed and celerity?

[mohlam12]

okay, just a simple question...
what is the difference between speed and celerity?
thanks :)

 

[Integral]

To the best of my knowledge "celerity" has no meaning in physics.

 

[robphy]

In relativity, celerity has been used to describe the quantity $$\frac{1}{\sqrt{1-v^2/c^2}}v$$, where $$v$$ is the velocity (whose magnitude is the speed).