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

“Speed is more important than efficiency or effectiveness right now,” Olive said.

From The Wall Street Journal • May 8, 2026

“Although law enforcement strives for 100% effectiveness with every tactic or tool used during confrontations, that’s not always the case,” Lt.

From Los Angeles Times • May 7, 2026

The agency first approved mifepristone in 2000, after evaluation of rigorous studies demonstrating its effectiveness and safety.

From Slate • May 4, 2026

Their effectiveness depends on a tightly controlled contact point called the "immune synapse," where they release toxic molecules that destroy the target while leaving surrounding healthy cells unharmed.

From Science Daily • Apr. 30, 2026

The organism remains viable in the soil for years and therefore be comes to all intents and purposes permanently established, increasing in effectiveness, and being continuously spread by natural agencies.

From "Silent Spring" by Rachel Carson

Related Words

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