effect

1. Origins, structure, and basic meaning

• Structure: 効 expresses taking effect and has the on-reading こう. The words 効く and 効果 are read きく and こうか, respectively.
• Basic usage: 効く can describe medicine working or a spice having a noticeable flavor in food.

2. Common pitfalls and similar expressions

• A Korean gloss
  • The Korean gloss of 効く that also means hearing is used here in the sense of medicine working. It does not describe the act of hearing a sound.
• Noun and verb
  • 効果 is a noun referring to an effect, while 効く describes taking effect. 効いている describes an effect or flavor being noticeable.