Longman Dictionary of Contemporary English homepage

invalidate

verb
     
in‧val‧i‧date [transitive]
1 to make a document, ticket, claim etc no longer legally or officially acceptable:
Failure to disclose all relevant changes may invalidate your policy.
2 to show that something such as a belief or explanation is wrong:
Later findings invalidated the theory.

Dictionary pictures of the day
Do you know what each of these is called?
What is the word for picture 1? What is the word for picture 2? What is the word for picture 3? What is the word for picture 4?
Click on any of the pictures above to find out what it is called.

Explore our topic dictionary