効

音読おんよみ: コウ

訓読くんよみ: きく

画数かくすう: 8

部首ぶしゅ: 力（ちから）

Meaning

Effect / Benefit / Efficiency

  • Basic forms
  • 効く — to work; to be effective / base form
  • 効きます — works; is effective / masu form
  • 効いた — worked; was effective / ta form
  • 効いて — working; being effective and … / te form
  • 効かない — does not work; is ineffective / negative
  • 効けば — if it works / conditional
  • 効け — work! (rare) / imperative
  • Common uses
  • 薬が効く — medicine works
  • よく効く — works well
  • 効果が効く — be effective (formal)
  • More
  • 効き目 — effect; efficacy

効く（きく） is a godan verb. It is used for medicine, skills, rules, or influences that produce a real effect, rather than for deliberate actions by a person.

  • 効果こうか — effect / result
  • 有効ゆうこう — valid / effective
  • 効力こうりょく — efficacy / legal force
  • 効率こうりつ — efficiency
  • 実効じっこう — actual effect

効 combines 交 (phonetic) with 力 (power). It originally meant “to bring about through effort.” Today, it highlights results — from medicine (効能) to laws (効力) and processes (効率).

この薬くすりは よく効ききます。
This medicine works well.

ルールは 効果こうかを 発揮はっきしています。
The rules are proving effective.

率
Creates
効率こうりつ — efficiency
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