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

But despite its effectiveness in eliminating polio, the live virus occasionally mutated back into its pathogenic form, resulting in rare cases of vaccine-related polio—something that Sabin refused to acknowledge.

From The Wall Street Journal • Jun. 21, 2026

The loss of Gilmour is a key point to consider when talking about McTominay's effectiveness.

From BBC • Jun. 20, 2026

However, in an analysis of two popular BIP models, the National Institute of Justice concluded that their effectiveness was mixed.

From Slate • Jun. 15, 2026

In addition to their limited effectiveness, opioids were linked to a higher risk of side effects in several situations, including acute musculoskeletal pain, traumatic limb injuries, and some forms of post surgical pain.

From Science Daily • Jun. 9, 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