1. Noun which may take the genitive case particle 'no', Na-adjective (keiyodoshi), Noun

   1.

   invalid; void; ineffective; unavailable

2. Wikipedia definition

   2.

   Void (law)

Example sentences

• 明日から、このメールアドレスは無効になります。

  Starting tomorrow, this e-mail address will no longer be valid.

• 無理矢理サインさせられたのなら、その契約は無効ですよ。

  The contract, if you were forced to sign it, is invalid.