How to say "valid" in Japanese

• 有効ゆうこうJLPT N3approx.Common
  na-adjective, nounCovers 'valid' in the sense of being in force or effective: a ticket, passport, contract, or method that still works or counts. It emphasizes that something currently has effect, not that it is reasonable.
  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.
• 妥当だとうJLPT N2approx.Common
  na-adjective, noun, suru verb, intransitive verbCovers 'valid' in the sense of proper, right, or appropriate: a judgment, conclusion, decision, or argument that is reasonable and well founded. It evaluates soundness of thinking rather than whether something is in force.
  彼女かのじょの選曲せんきょくが妥当だとうだったとは思おもわない。↗

  I do not consider her choice of music a happy one.

Use 有効 for something officially or practically in force and effective, such as a ticket or contract; use 妥当 for a judgment, conclusion, or argument that is reasonable and appropriate.

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

• 有効ゆうこうvalid
• 妥当だとうvalid
• バリッドvalid
• 合式ごうしきformal