Translation

無効な / 正しくない / 根拠のない

Meaning

Invalid means not legally, logically, or officially acceptable. It is used for tickets, passwords, arguments, contracts, votes, data, and forms. The learner trap is pronouncing it like the old health noun invalid.

Examples

• このチケットは昨日で無効になりました。
  This ticket became invalid yesterday.
• その議論は誤った前提に基づいているので無効です。
  The argument is invalid because it is based on a false assumption.