effectiveness

American

[ih-fek-tiv-nis, ee-fek‐] / ɪˈfɛk tɪv nɪs, iˈfɛk‐ /

Rarely effectivity

noun

the quality of producing an intended or desired result.

For maximum effectiveness of your weight loss plan, you need to combine exercise with a healthy diet.
the quality of producing a deep or vivid impression.

We were struck by the evident appeal and effectiveness of these short, dramatic, upbeat video stories.
a measure of the success of a vaccine or other pharmaceutical when used in the real world, as opposed to the controlled environment of a clinical trial.

Other Word Forms

subeffectiveness noun
supereffectiveness noun
uneffectiveness noun

Etymology

Origin of effectiveness

First recorded in 1600–10; effective ( def. ) + -ness ( def. )

Vocabulary lists containing effectiveness

Reading: Informational - Middle School

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Media Literacy - High School

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Media Literacy - Middle School

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

One example is extensive, independent testing to ensure the effectiveness and reliability of critical systems, which can mean life or death for servicemembers.

From The Wall Street Journal • Apr. 16, 2026

According to media reports, the study used hospital patients’ vaccination status to calculate the success of the season’s vaccine, a method long used to determine flu vaccine effectiveness.

From Los Angeles Times • Apr. 14, 2026

By analysing millions of their genetic variants, the researchers found a pattern suggesting a link between some variants and the effectiveness of the drugs.

From BBC • Apr. 8, 2026

They can also be engineered to carry multiple components, increasing their potential effectiveness.

From Science Daily • Apr. 2, 2026

Lupita let out a deep sigh of sadness, asking herself if even the effectiveness of hard work could be trusted.

From "Lupita Mañana" by Patricia Beatty

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023