有効|ゆうこうyuukou[0]heiban (flat)

1. na-adjective, nounvalid; effective
   その切符きっぷは一いち週間しゅうかん有効ゆうこうです。↗

   The ticket is valid for a week.
2. noun, martial artsyuko (judo)

• Synonym効果的こうかてきNeutralStresses that a method produces clear, visible results, as in 「効果的な練習」; 「有効」 also covers the legal validity of documents and contracts.
• Related妥当だとうWrittenWritten/formal word for judgments and actions that are reasonable and appropriate, as in 「妥当な判断」; it does not indicate whether something works or a document is valid.
• Related効率的こうりつてきNeutralEmphasizes saving time and effort with no waste, as in 「効率的に作業する」; 「有効」 focuses on having an effect, as in 「時間を有効に使う」.
• Related実用的じつようてきNeutralMeans usable in real life, as in 「実用的な贈り物」 or 「実用的な知識」; it is about practical use, not the validity or force that 「有効」 can denote.
• Related役立つやくだつNeutralA verb meaning to come in handy or help, common in speech; 「有効」 is a na-adjective, as in 「有効期限」.
• Related有用ゆうようWrittenWritten/formal word for something useful or valuable, as in 「有用な情報」; it does not cover legal validity or validity within a period.
• Related有益ゆうえきWrittenWritten/formal word stressing that something brings benefit, as in 「有益な話」; 「有効」 is about whether something works or carries validity.
• Antonym無効むこうNeutralThe antonym: it is the opposite of 「有効」 in both senses — no effect, void, or not working, as in 「無効な切符」.

Use 「有効」 for documents and tickets that are still in force, as in 「有効期限」 (the period of validity), and for methods that work, as in 「時間を有効に使う」. Choose 「効果的」 for visible results, 「効率的」 for saving time and effort, 「有益」 for benefit, and 「無効」 as the opposite.

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

1. 効力こうりょくがあること。
2. 役やくに立たつ様子ようす。意図いとした通とおりに影響えいきょうが出でているさま。有意義ゆういぎ。効率的こうりつてき。
3. 柔道じゅうどうなど素手すでの武道ぶどうにおいて、一いち本ぽん・技わざありには満みたない程度ていどの投げ技なげわざ、突つき技わざ、蹴り技けりわざ、打うち技わざなどを決きめた事ことを評価ひょうかする呼称こしょう。