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

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

Users hit back at Papperger's comments with jokes and memes highlighting the effectiveness of Ukrainian drones and anti-drone defences.

From Barron's • Mar. 29, 2026

This research shows that effectiveness depends not only on whether a drug reaches a tumor, but also on how it spreads within it and inside individual cells.

From Science Daily • Mar. 27, 2026

Brainy committees are continually evaluating the effectiveness and cost of doing various things in space, defense, energy, transportation, and the like, to give advice about prudent investments for the future.

From "The Lives of a Cell" by Lewis Thomas

Related Words

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