Mad As a Hatter (Origin)

by Craig Shrives

What Is the Origin of the Saying "Mad As a Hatter"?

To be as mad as a hatter means to be crazy or to behave unpredictably.

The term comes from the hat-making industry in the middle ages, which used the highly toxic mercury nitrate in the hat’s rim. The people who made these hats would often suffer poisoning which would make them act oddly. Therefore, many hatters were assumed to be crazy.
As Mad As a Hatter (Origin)

Previous and Next Sayings

Test Your Knowledge of English Proverbs and Idioms

Ready for the Test?

More Proverbs, Sayings, and Idioms

Help Us Improve Grammar Monster

  • Do you disagree with something on this page?
  • Did you spot a typo?

Find Us Quicker!

  • When using a search engine (e.g., Google, Bing), you will find Grammar Monster quicker if you add #gm to your search term.

See Also

What are idioms? What is figurative language? A list of common grammar errors A list of easily confused words A list of sayings and proverbs