effective

 
Pronunciation: /ɪˈfɛktɪv/

adjective

  • 1successful in producing a desired or intended result: effective solutions to environmental problems
  • (of a law, rule, or policy) operative: the regulation will be effective from January
  • 2 [attributive] existing in fact, though not formally acknowledged as such: she has been under effective house arrest since September
  • assessed according to actual rather than face value: an effective price of £176 million

noun

  • a soldier fit and available for service: when the battles broke out, he had a total of 920 effectives

Derivatives

effectivity

Pronunciation: /-ˈtɪvɪti/
noun

Origin:

late Middle English: from Latin effectivus, from efficere 'accomplish' (see effect)