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

Research by the International Monetary Fund finds that rule of law is necessary for long-term economic growth and that “within the rule of law, the effectiveness of the justice system…are critical to economic outcomes.”

From Barron's • Apr. 1, 2026

The trend continued into the 1990s, with the likes of Roger Clemens, Curt Schilling and John Smoltz deploying it with deadly effectiveness.

From The Wall Street Journal • Mar. 31, 2026

Despite doubts about their effectiveness, Minicircle’s gene therapy and others like it are available at an increasing number of clinics across the world.

From Slate • Mar. 30, 2026

Gaining a better understanding of how these drugs are stored and distributed inside cells could lead to more personalized treatment strategies, improving effectiveness while reducing resistance and relapse.

From Science Daily • Mar. 27, 2026

Then Ambady compared those snap judgments of teacher effectiveness with evaluations of those same professors made by their students after a full semester of classes, and she found that they were also essentially the same.

From "Blink" by Malcolm Gladwell

Related Words

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