What does efficacy mean?

Definitions for efficacy
ˈɛf ɪ kə sief·fi·ca·cy

Here are all the possible meanings and translations of the word efficacy.

Princeton's WordNet

  1. efficacy, efficaciousnessnoun

    capacity or power to produce a desired effect

    "concern about the safety and efficacy of the vaccine"


  1. efficacynoun

    Ability to produce a desired amount of a desired effect.

    Etymology: From efficacia, from efficax; see efficacious.

Webster Dictionary

  1. Efficacynoun

    power to produce effects; operation or energy of an agent or force; production of the effect intended; as, the efficacy of medicine in counteracting disease; the efficacy of prayer


  1. Efficacy

    Efficacy is the capacity to produce an effect. It has different specific meanings in different fields. In medicine, it is the ability of an intervention or drug to produce a desired effect.

Editors Contribution

  1. Efficacy

    Efectividad manifiesta.

    Submitted by ector on March 31, 2019  

Matched Categories

How to pronounce efficacy?

How to say efficacy in sign language?


  1. Chaldean Numerology

    The numerical value of efficacy in Chaldean Numerology is: 3

  2. Pythagorean Numerology

    The numerical value of efficacy in Pythagorean Numerology is: 4

Examples of efficacy in a Sentence

  1. Jamie Triccas:

    The main thing is we want to stop deaths, that's the first thing you want. If you vaccinate as many as you can, you know the vaccine may not stop all people from getting infected but those are good at stopping serious infections, hospitalizations and death, time is not on our side. We're in a situation where we're having more deaths and cases per day than ever. It's time to cooperate and move all vaccines out as quickly as possible, as long as they're safe and have a level of efficacy that's agreed on as being effective.

  2. Danny Altmann:

    The efficacy looks good, including in the over 60s, it’s good to have another addition to the global arsenal.

  3. Paul Mango:

    We're dealing in a world of great uncertainty, we don't know the timing of when we'll have a vaccine. We don't know the quantities. We don't know the efficacy of those vaccines.

  4. Justin Beck:

    The FDA has been diligent in avoiding political pressure by maintaining a balance of speed to market and obtaining data sufficient to provide emergency use authorization, while we cant yet confirm the long-term efficacy or safety of COVID-19 vaccines, there is enough data to confirm at least three are safe and effective.

  5. Gregory Glenn:

    Different continent, different population, different viruses floating around, and yet, we still see really good efficacy, this is what you want to have.

Images & Illustrations of efficacy

  1. efficacyefficacyefficacyefficacyefficacy

Popularity rank by frequency of use


Translations for efficacy

From our Multilingual Translation Dictionary

Get even more translations for efficacy »


Find a translation for the efficacy definition in other languages:

Select another language:

  • - Select -
  • 简体中文 (Chinese - Simplified)
  • 繁體中文 (Chinese - Traditional)
  • Español (Spanish)
  • Esperanto (Esperanto)
  • 日本語 (Japanese)
  • Português (Portuguese)
  • Deutsch (German)
  • العربية (Arabic)
  • Français (French)
  • Русский (Russian)
  • ಕನ್ನಡ (Kannada)
  • 한국어 (Korean)
  • עברית (Hebrew)
  • Gaeilge (Irish)
  • Українська (Ukrainian)
  • اردو (Urdu)
  • Magyar (Hungarian)
  • मानक हिन्दी (Hindi)
  • Indonesia (Indonesian)
  • Italiano (Italian)
  • தமிழ் (Tamil)
  • Türkçe (Turkish)
  • తెలుగు (Telugu)
  • ภาษาไทย (Thai)
  • Tiếng Việt (Vietnamese)
  • Čeština (Czech)
  • Polski (Polish)
  • Bahasa Indonesia (Indonesian)
  • Românește (Romanian)
  • Nederlands (Dutch)
  • Ελληνικά (Greek)
  • Latinum (Latin)
  • Svenska (Swedish)
  • Dansk (Danish)
  • Suomi (Finnish)
  • فارسی (Persian)
  • ייִדיש (Yiddish)
  • հայերեն (Armenian)
  • Norsk (Norwegian)
  • English (English)

Word of the Day

Would you like us to send you a FREE new word definition delivered to your inbox daily?

Please enter your email address:

Discuss these efficacy definitions with the community:



    Use the citation below to add this definition to your bibliography:


    "efficacy." Definitions.net. STANDS4 LLC, 2021. Web. 30 Nov. 2021. <https://www.definitions.net/definition/efficacy>.

    Are we missing a good definition for efficacy? Don't keep it to yourself...

    Browse Definitions.net

    Free, no signup required:

    Add to Chrome

    Get instant definitions for any word that hits you anywhere on the web!

    Free, no signup required:

    Add to Firefox

    Get instant definitions for any word that hits you anywhere on the web!


    Are you a words master?

    irregularly slashed and jagged as if torn
    • A. tantamount
    • B. numinous
    • C. lacerate
    • D. dicotyledonous

    Nearby & related entries:

    Alternative searches for efficacy: