effective

adj

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

   “The pill is an effective method of birth control.”

   “"Capital idea; we'll go together and complain: two will be more effective," suggested Mr. Belting.”

   “Fire ants circumvented the problem of an ineffective sting by having an unusual and highly effective venom that when daubed or sprayed on other ants penetrates their waxy protective integumental barrier and kills or disables them.”

2. Producing a decided or decisive effect.

   “The president delivered an effective speech!”

   “Whosoever is an effective, real cause of doing his neighbour wrong, is criminal.”

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. Having no negative coefficients.
6. Such that no group element acts trivially.
7. approximate; Not describing the fundamental dynamic changes in some system as they happen.

noun

1. a soldier fit for duty

   “The Army of the West reached Corinth sometime after the battle of Shiloh. We were 15,000 effectives, and brought Beauregard's effective force up to 45,000 men.”