Definition of effective adjective from the Oxford Advanced Learner's Dictionary



    BrE BrE//ɪˈfektɪv//
    ; NAmE NAmE//ɪˈfektɪv//
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  1. 1  producing the result that is wanted or intended; producing a successful result Long prison sentences can be a very effective deterrent for offenders. Aspirin is a simple but highly effective treatment. drugs that are effective against cancer Some people believe that violence is an effective way of protesting. I admire the effective use of colour in her paintings. opposite ineffective see also cost-effective
  2. 2[only before noun] in reality, although not officially intended the effective, if not the actual, leader of the party In spite of what they are told, parents have no effective choice of schools. He has now taken effective control of the country.
  3. 3(formal) (of laws and rules) coming into use The new speed limit on this road becomes effective from 1 June.
  4. Word Originlate Middle English: from Latin effectivus, from efficere ‘accomplish’, from ex- ‘out, thoroughly’ + facere ‘do, make’.Extra examples The drug is generally effective in reducing pain. This method is effective enough with greenfly. We find advertising on the radio very effective. What makes a TV programme politically effective? a highly effective technique directly effective treaty provisions effective at keeping out the wind effective in helping people to stop smoking He argued that long prison sentences could be a very effective deterrent for offenders.
See the Oxford Advanced American Dictionary entry: effective