invalid

invalid — adjective

1. used to describe a document, ticket, law, or agreement that has no legal force b

1.adjectiveB1
Definition

used to describe a document, ticket, law, or agreement that has no legal force because it does not follow the required rules.

Example

Élise's passport was declared invalid because it had expired three months earlier.

passive: be declared invalid

The court ruled that the old contract was invalid and could not be enforced.

ruled + that-clause + invalid

Common collocations
  • declare invalid
  • rule invalid
  • considered invalid
  • invalid contract
  • invalid passport
  • invalid ballot
Synonyms
  • void

    suggests something never had legal effect, often from the very beginning

  • null

    often paired with 'void' in legal phrases (null and void); highly formal

  • lapsed

    means was valid before but expired, like a membership or insurance policy

Antonyms
  • valid

    the direct opposite; legally or officially acceptable

Usage Note

Frequently used in passive constructions with verbs like 'declare,' 'rule,' and 'consider.' The object is typically a legal or official document (passport, contract, ballot).

Common Mistakes

The signature is invalided.
The signature is invalid.
'invalided' is a verb form meaning 'removed from duty'; the adjective has no -ed suffix.

2. used to describe an argument, reason, or opinion that is wrong because it is bui

2.adjectiveB2
Definition

used to describe an argument, reason, or opinion that is wrong because it is built on faulty reasoning or incorrect facts.

Example

Lien's argument was invalid because it assumed a cause without offering any evidence.

argument + be + invalid + because-clause

The professor pointed out that the student's reasoning was invalid from the start.

pointed out + that-clause + reasoning + be + invalid

Common collocations
  • invalid argument
  • invalid reasoning
  • invalid conclusion
  • invalid premise
Synonyms
  • unsound

    suggests the reasoning has a hidden weakness; slightly more formal

  • fallacious

    implies a recognizable error in logic; quite formal

  • flawed

    softer than invalid; suggests a mistake rather than complete wrongness

Antonyms
  • valid

    logically correct and well-founded

  • sound

    strong and reliable in reasoning

Usage Note

Common with nouns of reasoning: 'argument,' 'reasoning,' 'conclusion,' 'premise.' Distinguish from sense 1 (NOT LEGALLY ACCEPTABLE): sense 2 deals with logical flaws, not legal standing.

invalid — noun

invalid — verb

Word family

Synonym discussion

Sense: adjective/1

All four words describe something that lacks legal force, but they differ in scope and timing. Invalid focuses on a failure to meet formal requirements — a contract signed without proper witnesses, for example. Void goes further, suggesting the document never had any legal effect at all, as if it were a nullity from the very beginning. Null is often paired with void (null and void) in legal language and carries the same sense of complete absence of effect. Lapsed is narrower: it describes something that was once valid but lost its force through the passage of time, such as an insurance policy or a gym membership. Use invalid for everyday problems with documents and tickets, void for legal judgments of complete nullity, and lapsed for agreements that expired.

void ↗null ↗invalid ↗lapsed

Common collocations

Phrases

  • declare invalid
  • rule invalid
  • considered invalid

Prepositions

Etymology

LatinFrenchEnglish

The word comes from Latin invalidus, meaning 'not strong' (in- meaning 'not' and validus meaning 'strong'). It passed into English through French invalide during the 1500s. The adjective meaning 'not legally valid' appeared first, while the noun meaning 'sick person' (pronounced differently, with stress on the first syllable) developed later from the same root.