If the unit or quantity in respect of which something is changing is not specified usually the rate is per unit time. Rate-and-term refinancing activity often occurs in response to a decline in prevailing. Just like in math Whats does constant term mean in math.
If the denominator of the ratio is expressed as a single unit of one of these quantities and if it is assumed that this quantity can be changed systematically ie is an independent variable then the numerator of the ratio expresses the corresponding rate of change in the other dependent variable.
Rate of change is the ratio that shows the relations hip between the two variables in equation. To place in a certain rank class etc as a ship or a sailor. To fix at a certain rate as of charge or payment. In other cases it refers to the rate of change such as in a derivative.