药物是用来治病的东西，医生开药以后，我们要按时吃药。

"药物" are substances used to treat illnesses; after the doctor prescribes them, we must take the "药物" on time.

这个词比较正式，常常在医院或者说明书上看到。

This word is more formal and is often seen in hospitals or instruction leaflets.