If something is efficacious, it works in the way you intended: it has the power to produce the right result. Doctors, scientists, and rather formal writers like this word — an efficacious medicine, an efficacious method, an efficacious treatment.

If something is efficacious, it works in the way you intended: it has the power to produce the right result如果一個東西是efficacious，它就是照你原本想的方式起作用：有能力產生對的結果 Doctors, scientists, and rather formal writers like this word — an efficacious medicine, an efficacious method, an efficacious treatment醫生、科學家和比較正式的寫作者喜歡這個字——an efficacious medicine（有效的藥）、an efficacious method（有效的方法）、an efficacious treatment（有效的療法）

It does not mean the thing is quick, cheap, or neat. It means it actually does the job.

It does not mean the thing is quick, cheap, or neat這不代表這個東西快、便宜或俐落 It means it actually does the job它的意思是這東西真的有效果、真的達成目的

In ordinary talk, people just say it works, or it is effective. Efficacious sounds like a paper or a textbook.

In ordinary talk, people just say it works, or it is effective在日常對話裡大家就會直接說it works，或說it is effective Efficacious sounds like a paper or a textbookefficacious聽起來像是論文或教科書裡的字

Though actually, students often reach for efficient by mistake. Efficient is about little waste: a fast route, a clever use of time. A medicine can be slow and still be efficacious; a machine can be efficient and still do the wrong thing.

Though actually, students often reach for efficient by mistake不過其實學生常常會不小心用成efficient Efficient is about little waste: a fast route, a clever use of timeefficient講的是浪費得少：一條快速的路線、一種聰明運用時間的方式 A medicine can be slow and still be efficacious; a machine can be efficient and still do the wrong thing一種藥可以很慢，但還是efficacious（有效）；一台機器可以很efficient（有效率），卻還是做錯事

In Taiwan you may also hear a warmer everyday cousin for remedies, 靈驗, when something really helps — but efficacious itself stays in the formal English of tests and research.

In Taiwan you may also hear a warmer everyday cousin for remedies, 靈驗, when something really helps在台灣，講到偏方真的有用時，你也會聽到一個比較親切、日常的說法：靈驗 but efficacious itself stays in the formal English of tests and research但efficacious這個字本身，還是留在測試和研究那種正式英文裡