1520s, from Latin efficacia "efficacy, efficiency," from efficax (genitive efficacis) "powerful, effectual, efficient," from stem of efficere "work out, accomplish" (see effect (n.)). Earlier in same sense was efficace (c. 1200), from Old French eficace (14c.), from Latin efficacia; also efficacite (early 15c.), from Latin efficacitatem.
中文解释
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。
实用例句
1. Recent medical studies confirm the efficacy of a healthier lifestyle.
最新医学研究证实了较为健康的生活方式的好处。
来自柯林斯例句
2. This plan would have some efficacy in preventing any danger.
这计划对于防止危险会有些效力.
来自《现代英汉综合大词典》
3. The treatment has no efficacy in that disease.
这种疗法对那种疾病不管事.
来自《现代汉英综合大词典》
4. Self - efficacy ( SE ) is being applied into computer use, which was defined as computer self - efficacy ( CSE ).