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.

---

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 effectiveness of the measure at the World Cup is open to debate, as there will be a three-minute hydration break in each half, creating a natural timeout for coaches.

From BBC • May 31, 2026

The next step will be larger Phase III clinical trials designed to confirm the drug's safety and effectiveness in a broader patient population before regulators consider approval.

From Science Daily • May 27, 2026

But that tactic no doubt exists, particularly with the less scrupulous agents out there,” said Andy Panko, a certified financial planner who is tracking IUL policy claims and testing their effectiveness in a continuing project.

From MarketWatch • May 27, 2026

Sticking with existing rules could “impact the overall index’s effectiveness as a benchmark,” S&P Dow Jones Indices suggested in the launch of its consultation.

From The Wall Street Journal • May 27, 2026

The great joke about Puttenham, though, is that he survives not only for his work on rhetoric but as an instance of its effectiveness.

From "Words Like Loaded Pistols" by Sam Leith

Related Words

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