/ ɪˈfektɪv; NAmE / adjective
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
I admire the effective use of colour in her paintings.
OPP ineffective
—see also cost-effective
2.
[ only before noun ] in reality, although not officially intended :
the effective, if not the actual, leader of the party
He has now taken effective control of the country.
3.
( formal ) ( of laws and rules ) coming into use :
The new speed limit on this road becomes effective from 1 June.
► ef·fect·ive·ness (also less frequent ef·fect·iv·ity / ɪˌfekˈtɪvɪti; NAmE /) noun [ U ]:
to check the effectiveness of the security system
••
WORD ORIGIN
late Middle English : from Latin effectivus , from efficere accomplish, from ex- out, thoroughly + facere do, make.