1. ef- "out" + fic- + -acy. 在这里取 out 的引申义:完成、结束(finish, end)之意。
2. meaning: 事情做完了,事情做结束了. => work out, accomplish.
3. => 引申为:事情做完、做结束后的效果。=> 效果、功效。
4. efficacy + 变 y 为 i 加 -ous.
英文词源
efficacious
efficacious: see effect
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.
双语例句
1. They hope the new drug will prove especially efficacious in the relief of pain.
他们希望这种新药能在缓解疼痛方面产生特效。
来自《权威词典》
2. It occurs to me that example is always more efficacious than precept.
我想到身教重于言教.
来自《简明英汉词典》
3. Qingdao is a resort efficacious for a variety of bodily ills.