invalid

Meanings

1. 1adjectivenot comparable

   Not accepted by law or by official rules, so it has no force or cannot be used.

   Grammar: Used after be or before a noun: an invalid passport.

   Patterns

   • an invalid ticket
   • declare something invalid

   The judge ruled the contract invalid because it was unsigned.

   Your ticket is invalid after midnight.

   The system rejected the invalid password.

2. 2adjectivecomparable

   Wrong because it rests on a mistake in reasoning or facts, so it cannot be relied upon.

   Grammar: Describes arguments, results or tests: an invalid argument.

   Patterns

   • an invalid argument
   • an invalid conclusion

   Her argument is invalid because it starts from a false claim.

   The results were invalid since the test was badly designed.

   He drew an invalid conclusion from the data.

3. 3adjectivebefore a nouncomputing

   Not in the correct form for a computer program to accept.

   Grammar: Often seen in error messages: invalid input.

   Patterns

   • invalid input
   • an invalid entry

   The form displayed an invalid email address error.

   Enter a number, because letters are invalid here.

   The program crashed after reading an invalid file.

4. 4nouncountableold-fashioned

   A person who is weak or disabled because of long illness or injury.

   Grammar: Stressed on the first syllable (IN-va-lid); now old-fashioned and can sound unkind.

   Patterns

   • an invalid

   In the novel, the old invalid rarely left his room.

   She spent years caring for her invalid mother.

   The word invalid for a sick person now sounds outdated.

Word forms

Common combinations

invalid password

You entered an invalid password.

declared invalid

The election was declared invalid.

invalid argument

That is an invalid argument because it contradicts itself.

invalid license

He was fined for driving with an invalid license.

invalid claim

The insurer rejected the invalid claim.

Synonyms and how they differ

void

Void is a legal word meaning having no legal effect from the start, and it is stronger than invalid.

unacceptable

Unacceptable means not good enough, whereas invalid means failing a formal or logical test.

unsound

Unsound describes weak reasoning or structure and does not apply to tickets or forms.

expired

Expired means it was valid once but time ran out, while invalid may never have been valid.

Opposites

Word family

invalidate verb

to make something no longer valid

invalidity noun

the state of being not valid

validity noun

the quality of being acceptable or correct

invalidation noun

the act of making something invalid

Commonly confused: invalid or in-valid?

Practice

Make it your own

Write a sentence using “invalid”, then check it and compare it with the examples above.

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