efficacy
EF-ih-kuh-see
/ˈef.ɪ.kə.si/
The ability to produce a desired or intended result; effectiveness.
In medical and scientific contexts, efficacy specifically refers to performance under controlled, ideal conditions.
The story behind the word. From Latin 'efficacia' (effectualness), stemming from 'efficere' (to bring about, accomplish). It emphasizes the power to accomplish a targeted outcome.
Word relationships
- effectiveness: Effectiveness is general success in real-world application, whereas efficacy often implies tested potential.
- inefficacy: Failure to produce the desired power or result.
- ineffectiveness: Lacking the capacity to achieve intended goals.
Commonly confused with
- efficiency: Efficacy is achieving the goal; efficiency is achieving it with minimal waste.
Word family
- efficacious (adjective): Successful in producing a desired or intended result.
Collocations
- demonstrate efficacy
- vaccine efficacy
- self-efficacy
Example sentences
- "Clinical trials demonstrated high efficacy for the new antiviral medication." Medicine
Memory hook
EFFICACY is the EFFORT that produces EFFEcts. Power to produce results.
When not to use
Do not confuse with 'efficiency', which refers to minimizing wasted energy or resources.
Fun facts
- In pharmacology, efficacy is measured in trials, whereas 'effectiveness' is measured in real-world clinics.
Related words
Explore more words
effective, effectively, efficiency, potency, agency, efficient
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