effective

From Wiktionary

[change] Pronunciation

•  Audio (US)^{help, file}

[change] Adjective

Positive effective

Comparative more effective

Superlative most effective

1. Something that can make or is making an effect.
2. Something that is efficient.

   as an effective force, remedy, speech

3. Something that is being used.

   The curfew is effective at midnight.

[change] Preposition

Preposition effective

1. Effective next week, all employees will wear the new uniform.

This short article needs someone to make it better. You can help Wiktionary by adding to it.