ds/dt is velocity (time rate of change of position)

d2s/dt2 is acceleration (time rate of change of velocity)

and d3s/dt3 is generally called "jerk", or time rate of change of acceleration.

The 1st derivative = ds/dt The 2nd derivative = d2s/dt2 The 3rd derivative = d3s/dt3 So d3s/dt3 means don't be a JERK.