producing the result that you want
Taking notes during class is an effective way to remember the material.
The mosquito spray was so effective that no one got bitten.
starting to be used and having legal or practical force
The new parking rules will be effective next Monday.
The price changes become effective at the start of the new year.
producing a strong or pleasing impression
The play used simple lights, but the results were very effective.
His effective speech inspired the whole audience.
in a successful or efficient way that produces the intended result
The new water filter effectively removed all the impurities from the river water.
By organizing her notes, Maria studied effectively for the exam.
✦ From adjective effective + adverbial suffix -ly, first recorded in the 15th century.
the state of being in force or legally operative
The contract’s effectiveness starts on July 1.
Parliament debated the legal effectiveness of the emergency decree.
✦ Same origin as Sense 1; extended in legal writing to mean “being in effect.”
