efficaciousness

noun

Definition of efficaciousnessnext
as in efficacy
the power to produce a desired result the efficaciousness of exercise in improving physical as well as emotional well-being

Synonyms & Similar Words

Relevance

Antonyms & Near Antonyms

Example Sentences

Recent Examples of Synonyms for efficaciousness
  1. efficacy
  2. effectiveness
Noun
  • Ferulic acid, for its part, can help boost their stability and efficacy—which in sum made the formula more powerful than most antioxidant serums.
    — Deanna Pai, Vogue, 7 Aug. 2026
  • But researchers cautioned that the drug’s efficacy has not yet been proven.
    — The New Yorker, New Yorker, 7 Aug. 2026
Definition of efficacy
Noun
  • The traditional flu shot ranges in effectiveness from 22% to 56%, according to the Mayo Clinic.
    — Berkeley Lovelace Jr, NBC news, 6 Aug. 2026
  • One of the reasons people are reluctant to get a flu shot is because of its sometimes weak effectiveness in protecting against symptoms.
    — Alice Park, Time, 6 Aug. 2026
Definition of effectiveness
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Browse Nearby Words

efficacious
efficaciousness
efficacity
See all Nearby Words

Cite this Entry

“Efficaciousness.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/efficaciousness. Accessed 10 Aug. 2026.

Copy Citation
Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

7 Pairs of Commonly Confused Words

Merriam-Webster’s Great Big List of Words You Love to Hate

Is that lie 'bald-faced' or 'bold-faced'?

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?
See More

Popular in Wordplay

See More

The Longest Long Words List

It's a Scorcher! Words for the Summer Heat

14 Phobias You Probably Haven't Heard Of

The Words of the Week - Aug. 7

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

7 Pairs of Commonly Confused Words

The Longest Long Words List

It's a Scorcher! Words for the Summer Heat
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
fridge-magnet-letters
Drop a Letter Quiz August 2026 Drop a letter from a word to make a totally diffe...
See All