Definition Of efficacious
(typically of something inanimate or abstract) successful in producing a desired or intended result; effective.
the vaccine has proved both efficacious and safe
Example Of efficacious
A small comparison study demonstrated that these two drugs are equally efficacious .
Another edict was issued on December 16, 1074, after a serious drought in north China earlier in the year, requesting the names of deities in shrines and temples known to respond efficaciously to requests for rain.
Are you questioning whether these acts have any efficaciousness ?
Both drugs were equally efficacious in improving auditory hallucinations and suspiciousness.
Clinical trials are in progress and research is ongoing for developing a safe and efficacious vaccine against the disease.