Efficacious (adjective)

1. Effective in producing a desired result.
2. Having the power to produce a desired effect or result.
3. Producing the intended or expected result.

Origin:

Late 16th century: from latin efficacius (from efficax, efficac- "effective") + -ious.

Examples:

1. The medicine was efficacious in treating the patient's symptoms.
2. The new treatment was proven to be more efficacious than the previous one.
3. The efficacious solution was a combination of medication and therapy.
4. The efficacious leader was able to unite the team and achieve their goals.
5. The efficacious method was able to produce the desired results quickly.