- efficacious
[efficacious 词源字典]
- efficacious: see effect
[efficacious etymology, efficacious origin, 英语词源] - efficacious (adj.)
- "sure to have the desired effect" (often of medicines), 1520s, from Latin efficaci-, stem of efficax "effectual, powerful" (see efficacy) + -ous. Related: Efficaciously; efficaciousness.