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

According to media reports, the study used hospital patients’ vaccination status to calculate the success of the season’s vaccine, a method long used to determine flu vaccine effectiveness.

From Los Angeles Times • Apr. 14, 2026

It claimed "stopping full-time pay for part-time work... could increase capacity and the effectiveness of current staff and allow for headcount reduction", which would "save around £270,000".

From BBC • Apr. 9, 2026

If developed for human use, this type of male contraceptive could be delivered as an injection given every three months or possibly as a patch to maintain effectiveness, Cohen said.

From Science Daily • Apr. 7, 2026

Yet Novo Nordisk plans to avoid the mistakes that hurt it during the last round, and will seek to hold on to its early lead by emphasizing the effectiveness of its pill.

From The Wall Street Journal • Apr. 1, 2026

Organizations and researchers have produced countless studies on the arts’ effectiveness and ability to engage children cognitively, emotionally, physically, and artistically: in other words, on a holistic level.

From "Music and the Child" by Natalie Sarrazin

Related Words

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