Join In
Twitter
YouTube
Weekly Newsletter
Libraries
A-Z Grammatical Terms
A-Z Confused Words
FAQs by Writers
A-Z Awkward Plurals
Punctuation Lessons
Common Mistakes
(ordered by seriousness) ESL Vocabulary Lists Parts of Speech Lists A-Z Idioms and Proverbs Tests and Games Top Tip Install a grammar checker
for your browser
(ordered by seriousness) ESL Vocabulary Lists Parts of Speech Lists A-Z Idioms and Proverbs Tests and Games Top Tip Install a grammar checker
for your browser
Mad As a Hatter (Origin)
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.
Table of Contents
- English Proverbs and Idioms Test
- More Proverbs, Sayings, and Idioms

Examples of Use:
- His behavior became increasingly erratic, leading people to believe he was as mad as a hatter.
- She had a wild imagination and unconventional ideas, earning her the reputation of being as mad as a hatter.
- The character in the story was portrayed as as mad as a hatter, adding a touch of eccentricity to the narrative.
- While his actions may seem nonsensical to others, he's just as mad as a hatter in his own unique way.
Previous and Next Sayings
English Proverbs and Idioms 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.