Definition of "effective" in English

adjective

1. Having the power to produce a required effect or effects.

   • The pill is an effective method of birth control.

2. Producing a decided or decisive effect.

   • The president delivered an effective speech!

3. Efficient, serviceable, or operative, available for useful work.

   • How long does it take to make a bunch of civilians an effective military force?
   • My effective income after taxes and child support is $500 a month.
   • The effective radiated power is determined by multiplying the transmitter power output with the antenna gain.
   • The effective voltage of an alternating current is 0.7 times its peak voltage.

4. Actually in effect.

   • effective immediately
   • The curfew is effective at midnight.

5. (geometry, of a cycle or divisor) Having no negative coefficients.

6. (algebra, of a group action) Such that no group element acts trivially.

7. (physics, for any effective theory) approximate; Not describing the fundamental dynamic changes in some system as they happen.

noun

1. (military) a soldier fit for duty