Definition

1. Noun:
   • The state of being invalid; lack of validity or legal force: The condition of not being acceptable according to the law, rules, or logic.
   • The condition of being disabled by illness or injury: (Archaic or formal) The state of being an invalid; chronic ill health or disability.

Examples of Usage

• Noun (Lack of validity):
  • The court ruled on the invalidity of the contract due to a missing signature.
  • Scientists pointed out the invalidity of the experimental method, which made the results unreliable.
• Noun (Ill health - less common):
  • His prolonged invalidity prevented him from returning to work. (This usage is now rare.)

Advanced Usage

• "Presumption of invalidity": A legal principle where something is assumed to be invalid unless proven otherwise.
  • In trademark law, a mark may be subject to a presumption of invalidity if it is merely descriptive.
• "Patent invalidity": A specific legal finding that a patent is not legally enforceable.
  • The company filed a lawsuit seeking a declaration of patent invalidity.

Variants and Related Words

• Invalid (adj): Not valid; without legal force. / (n, archaic): A person made weak or disabled by illness or injury.
  • Your parking permit is invalid. (adj)
• Invalidate (v): To make something invalid; to deprive of legal force.
  • New evidence may invalidate the previous theory.

Synonyms

• Nullity: The state of being legally void and invalid.
• Voidness: The quality of having no legal force or effect.
• Illogicality: The quality of being illogical (related to the first sense).
• Infirmity: The state of being physically weak, especially from old age or illness (related to the second sense).

Antonyms

• Validity: The quality of being logically or factually sound; legal acceptability.
• Soundness: The state of being in good condition; robustness.

Noun

1. illogicality as a consequence of having a conclusion that does not follow from the premisses