効能・功能|こうのうkounou[0]heiban (flat)

1. nouneffect; effectiveness; efficacy; virtue; benefit
   絵画かいがが有ゆうする第だい一いちの効能こうのうは見みる人ひとの目めのごちそうとなることである。↗

   The first virtue of a painting is to be a feast for the eyes.

• Synonym効き目ききめCasualColloquial. The degree to which a medicine or method works, as in 「効き目がある」; 「効能」 is used more to describe beneficial effects.
• Synonym効力こうりょくWrittenWritten/formal prose. Validity or force, especially legal effect, as in 「効力を失う」; the focus is on whether something has force or not.
• Synonym効果こうかNeutralNeutral and the most common word for effect, with a very broad range; 「効能」 stresses a beneficial action that brings good results.
• Synonym実効じっこうWrittenWritten/formal prose. Actual, practical effect, as in 「実効性」; stresses effects that actually materialize.
• Synonym効こうWrittenWritten/formal prose, a single character for efficacy; seen mostly in set phrases such as 「効を奏する」.
• Synonym利きききCasualColloquial. Effectiveness, also one's dominant hand or tasting; often a prefix, as in 「利き手」「利き酒」.
• Synonym効験こうけんWrittenWritten/formal prose and uncommon; efficacy, said mostly of medicines or prayers proving effective.
• Related利りWrittenWritten/formal prose. Benefit or profit, mostly in compounds; not specifically about efficacy.
• Related効用こうようWrittenWritten/formal prose. Use or utility, also an economics term; stresses usefulness rather than effect.
• RelatedプラスCasualColloquial loanword; a plus or something beneficial, as in 「プラスになる」.
• RelatedアドバンテージCasualColloquial loanword; an advantage or favorable position, mostly in sports and business.
• RelatedベネフィットNeutralNeutral loanword meaning benefit; used mostly in business and marketing.
• Related益えきNeutralAs ますます it is an adverb meaning 'more and more'; written 「益（えき）」 it means benefit, close in sense to 「効能」.

Use 「効能」 for the beneficial effects of medicines, hot springs and the like, as in 「温泉の効能」「読書の効能」. In speech say 「効き目」; for effects in general use 「効果」; for legal validity use 「効力」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 良よい結果けっかをもたらす働はたらき。ききめ。