term:

Effective

effective adj

1 : producing a desired effect [an revocation of the contract]
2 : capable of bringing about an effect [ assistance of counsel] see also ineffective assistance of counsel
3 : being in effect
4 of a rate of interest
: equal to the rate of simple interest that yields the same amount when the rate is paid once at the end of the interest period as a quoted rate of interest does when calculated at compound interest over the same period compare nominal
ef·fec·tive·ness n

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.