effectiveness

American  

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

Rarely effectivity

noun

1. 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.

2. 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.

3. 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.

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Other Word Forms

• subeffectiveness noun
• supereffectiveness noun
• uneffectiveness noun

Etymology

Origin of effectiveness

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

Example Sentences

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

If developed for human use, this type of male contraceptive could be delivered as an injection given every three months or possibly as a patch to maintain effectiveness, Cohen said.

From Science Daily • Apr. 7, 2026

He practices the things he has been taught, though it is difficult to gauge the effectiveness of his illusions on his own.

From "The Night Circus" by Erin Morgenstern

Related Words

• capability
• efficacy
• efficiency
• potency
• power
• success