Efficacy
Efficacy noun - The power to produce a desired result.
Usage example: questioned the efficacy of the alarms in actually preventing auto theft
Efficiency is a synonym for efficacy in effectiveness topic. In some cases you can use "Efficiency" instead a noun "Efficacy", when it comes to topics like ability, affect, cost-effectiveness. popular alternative
Efficiency
Efficiency noun - The power to produce a desired result.
Usage example: the proven efficiency of citizen patrols in reducing crime in urban neighborhoods
Efficacy is a synonym for efficiency in effectiveness topic. You can use "Efficacy" instead a noun "Efficiency", if it concerns topics such as ability, affect, effect, cost-effectiveness. popular alternative
Mutual synonyms
Related pairs
- ability and efficacy
- ability and efficiency
- capacity and efficacy
- capacity and efficiency
- power and efficacy
- power and efficiency
- force and efficacy
- force and efficiency
- strength and efficacy
- strength and efficiency
- performance and efficacy
- performance and efficiency
- effect and efficacy
- effect and efficiency
How words are described
| high | high efficacy | high efficiency |
| reasonable | reasonable efficacy | reasonable efficiency |
| actual | actual efficacy | actual efficiency |
| terrible | terrible efficacy | terrible efficiency |
| Other adjectives: greater, surprising, magical. | ||
Cite this Source
Efficiency and Efficacy. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/efficacy/efficiency
Efficacy & Efficiency. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/efficacy/efficiency>.
Efficiency or Efficacy. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/efficacy/efficiency.
Google Ngram Viewer shows how "efficacy" and "efficiency" have occurred on timeline