Translation

有効な / 正当な / 妥当な

Meaning

Valid means accepted as effective, correct, or usable according to rules, law, evidence, or a system. A valid ticket, passport, password, or argument meets the required conditions.

Examples

• このチケットは月曜日まで有効です。
  This ticket is valid until Monday.
• その契約は署名がないため有効ではありません。
  The contract is not valid without a signature.