effective

/əˈfɛktɪv/

/ɛˈfɛktɪv/

If your email outlining a plan to reduce office paper waste resulted in a 20 percent reduction in paper use, that means your plan was effective: it did what you wanted it to do.

The adjective effective has many shades of meaning, but you'll usually see it describing something that's able to produce a desired goal. Effective traces back to the Latin word effectivus, from efficere, meaning “work out, accomplish,” and that meaning still holds true. Something effective gets the job done. As President, hopefully your policies are effective. We also use effective for something real and in effect, like the effective price of gas, or your effective grounding.

Definitions of effective

1. adjective

   producing or capable of producing an intended result or having a striking effect
   “"an air-cooled motor was more effective than a witch's broomstick for rapid long-distance transportation"-LewisMumford”

   “effective teaching methods”

   “effective steps toward peace”

   “made an effective entrance”

   synonyms: effectual, efficacious

   hard-hitting, trenchant

   characterized by or full of force and vigor

   impelling

   markedly effective as if by emotional pressure

   impressive, telling

   producing a strong effect

   rough-and-ready

   crude but effective for the purpose at hand

   efficacious

   marked by qualities giving the power to produce an intended effect

   efficient

   being effective without wasting time or effort or expense

   potent, stiff, strong

   having a strong physiological or chemical effect

   impactful, powerful

   having great power or force or potency or effect

   useful, utile

   being of use or service

   antonyms:

   ineffective

   not producing an intended effect

   idle

   not in action or at work

   toothless

   lacking necessary force for effectiveness

   unproductive

   not producing desired results

   inefficacious

   lacking the power to produce a desired effect

   inefficient

   not producing desired results; wasteful

   powerless

   lacking power

   useless

   having no beneficial use or incapable of functioning usefully
2. adjective

   works well as a means or remedy
   “an effective reprimand”

   “a lotion that is effective in cases of prickly heat”

   synonyms:

   efficacious

   marked by qualities giving the power to produce an intended effect
3. adjective

   able to accomplish a purpose; functioning effectively
   “"people who will do nothing unless they get something out of it for themselves are often highly effective persons..."-G.B.Shaw”

   “effective personnel”

   synonyms: efficient

   competent

   properly or sufficiently qualified or capable or efficient
4. adjective

   exerting force or influence
   “the law is effective immediately”

   synonyms: good, in effect, in force

   operative

   being in force or having or exerting force
5. adjective

   existing in fact; not theoretical; real
   “a decline in the effective demand”

   “confused increased equipment and expenditure with the quantity of effective work done”

   synonyms:

   actual, existent

   presently existing in fact and not merely potential or possible
6. adjective

   ready for service
   “the fort was held by about 100 effective soldiers”

   synonyms:

   operational

   (military) of or intended for or involved in military operations