Understanding 効力 (こうりょく)
The word 効力 means "effect" or "efficacy," and it is often used to describe the power or effectiveness of something such as medicine, laws, contracts, or rules. It implies that something has a real, practical impact or legal force.
Usage Contexts
- Medicinal or practical effectiveness: When talking about medicine or treatments, 効力 refers to how strong or effective the medicine is.
- Legal or formal validity: It is commonly used to describe when contracts, laws, or official documents become valid or enforceable.
Common Collocations and Patterns
- 効力がある／ない: to have or not have effect
- 効力を発揮する: to demonstrate or exert effectiveness
- 効力を失う: to lose effectiveness
- 契約の効力: validity or effect of a contract
- 法律の効力: legal effect or force
Register and Nuance
Effort is generally formal and used in written or official contexts, such as legal documents, medical instructions, or formal discussions. It is not casual conversation vocabulary.
Learner Tips
A common confusion is mixing 効力 with 効果 (こうか), which also means "effect" or "result." 効力 emphasizes the power or legal force behind something, while 効果 focuses more on the outcome or result. For example, a medicine’s 効力 is its potency, while its 効果 is the symptom relief it provides.