rate of change,
n. 1. the ratio of the difference between values of a variable quantity at different times to the difference between the times; the change per unit time, that is,
If the quantity is continuously variable and this ratio tends to a limit as both endpoints of the time interval tend to the same point, the instantaneous rate of change is the derivative of the function with respect to time, at the point that represents that quantity. 2. more generally, any derivative: dy/dx is the rate of change of y with respect to x.
If the quantity is continuously variable and this ratio tends to a limit as both endpoints of the time interval tend to the same point, the instantaneous rate of change is the derivative of the function with respect to time, at the point that represents that quantity. 2. more generally, any derivative: dy/dx is the rate of change of y with respect to x.