Efficacious
adj.capable, hopefulformal
What it means
Successful in producing the intended result.
Reach for it when formally describing an intervention shown to achieve its stated aim
The review found the revised treatment both safe and efficacious.
Choose between these
6- everyday
when useful output or progress is the desired result
not when Productive is wrong for treatments or safeguards whose value is not output.
- everyday
when a completed attempt achieved its goal
not when Successful can depend on circumstances and does not isolate the intervention's effect.
- professional
when plain language can state that something works
not when Effective may report actual results without attributing inherent capacity.
- professional
when adequacy for a defined practical task has been tested
not when Fit for purpose sets a sufficiency bar and may understate strong evidence of effect.
- professional
when a substance or influence has strong power
not when Potent concerns strength and may increase harms as well as benefits.
- literary
when the effect is beneficial, especially after correction
not when Salutary means beneficial rather than demonstrably capable of working.
Said against
4- inefficacious
- ineffective
- futile
- impotent
It naturally appears in
3- safe and efficacious
The panel required evidence that the therapy was safe and efficacious.
- clinically efficacious
A clinically efficacious drug may still be difficult to deliver equitably.
- prove efficacious
The simpler protocol may prove efficacious in community clinics.
Where this comes from
- wiktionary, English adjective, adjective sense meaning capable of producing the intended effect opens in a new tab · retrieved 2026-07-26
The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.