Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “effective”

See all translations

effective

adjective uk   /ɪˈfek.tɪv/ us  

effective adjective (SUCCESSFUL)

B2 successful or achieving the results that you want: It's an extremely effective cure for a headache. The lighting for the production made a very effective use of shadow. She's a very effective teacher.
Opposite
More examples

effective adjective (IN FACT)

[before noun] in fact, although not officially: Although she's not officially our boss, she's in effective control of the office.

effective adjective (IN USE)

If a law or rule becomes effective, it starts to be used: The new laws will become effective next month.
effectiveness
noun [U] uk   /-nəs/ us  
C1 There are doubts about the effectiveness of the new drug (= how successful it is) in treating the disease.
(Definition of effective from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of effective?
Add Cambridge dictionaries to your browser to your website

More meanings of “effective”

Definitions of “effective” in other dictionaries

Word of the Day

comma

the symbol , used in writing to separate parts of a sentence showing a slight pause, or to separate the single things in a list

Word of the Day

Lies, lies, lies!

by Kate Woodford,
February 25, 2015
​​​ According to sociologists (=people who study the relationships between people living in groups), we are good at lying. As a species, we have developed a remarkable ability to deceive each other (= persuade each other that something false is true). Being able to say things that are not true can help with

Read More 

showrooming noun

February 23, 2015
the activity of examining a product in a physical store and then making the purchase with an online retailer Amazon’s new smartphone is specifically designed to make showrooming fast and easy.

Read More