Efficacy is defined as the ability to do what is defined as desired or to be effective at producing a result.
An example of efficacy is when a crime bill is effective at stopping crime.
power to produce effects or intended results; effectiveness
Origin of efficacyMiddle English and Old French efficace from Classical Latin efficacia from efficax: see efficacious
Power or capacity to produce a desired effect; effectiveness.
Origin of efficacyLatin efficācia from efficāx efficāc- efficacious ; see efficacious .
- (uncountable) Ability to produce a desired amount of a desired effect.