efficacy
Definitions
The ability to produce a desired or intended result, especially of a drug or treatment.
功效，效力（尤指药物、疗法的）。
Root Breakdown
Root-derivedef- (ex-, 'out') + fic (fac, 'make/do') + -acy (quality) = 'the quality of being able to work something out.' Efficacy is the bare power to get the intended result — used in formal, often scientific contexts (drug efficacy, vaccine efficacy).
Root fac still carries 273 more wordsUsage Guide
- More formal/technical than effectiveness. Efficacy = does it work under ideal/controlled conditions (clinical trials); effectiveness = does it work in real-world use.
- Common in medicine, research, and policy writing.
Example Sentences
- 1.
Clinical trials confirmed the vaccine's high efficacy.
- 2.
Researchers questioned the efficacy of the new teaching method.
Easily Confused
efficacy vs efficiency — Both from the fic family but very different. Efficacy = whether it works at all (does the drug cure?). Efficiency = how little waste in getting there (does it cure fast and cheap?). Result vs resource use.