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be (as) mad as a hatter
1. To be crazy. Tim has been behaving very erratically lately, so I'm afraid that he's as mad as a hatter.
2. To be very angry. Mom was mad as a hatter after I dented her brand-new car.
(as) mad as a hatter
1. Crazy or deranged; particularly eccentric. My grandfather came back from the war as mad as a hatter because of all the horrible things he saw. I'll be mad as a hatter if I have to deal with these screaming toddlers for much longer. My family thinks I'm as mad as a hatter just because I practice a form of alternative medicine using magnetic fields.
2. Particularly cross or angry. Mom was mad as a hatter after I dented her brand-new car. John gets as mad as a hatter when he starts losing.
*mad as a hatterand *mad as a march hare
1. crazy. (Alludes to the crazy characters in Lewis Carroll's Alice's Adventures in Wonderland. *Also: as ~.) Poor old John is as mad as a hatter. All these screaming children are driving me mad as a hatter.
2. angry. (This is a misunderstanding of mad in the first sense. *Also: as ~.) You make me so angry! I'm as mad as a hatter. John can't control his temper. He's always mad as a hatter.
mad as a hatter
Also, mad as a March hare. Crazy, demented, as in She is throwing out all his clothes; she's mad as a hatter. This expression, dating from the early 1800s, alludes to exposure to the chemicals formerly used in making felt hats, which caused tremors and other nervous symptoms. The variant, dating from the 14th century, alludes to the crazy behavior of hares during rutting season, mistakenly thought to be only in March.
mad as a hattermainly BRITISH
If someone is as mad as a hatter, they are crazy. Her sister's as mad as a hatter and if you ask me she's not much better herself. Note: In the 19th century, `hatters' or hat-makers used nitrate of mercury to treat their fabrics. This substance is poisonous, and if the hat-makers breathed it in, they often suffered brain damage. As a result, hatters were traditionally thought of as mad. In Lewis Carroll's children's story `Alice in Wonderland' (1865), one of the characters is a hatter who behaves very strangely. Carroll may have based the character on a well-known Oxford furniture dealer, Theophilus Carter, who was known as the `Mad Hatter'.
mad as a hatter (or a March hare)completely crazy. informal
In this expression, a hatter refers to Lewis Carroll's character, the Mad Hatter, in Alice's Adventures in Wonderland ( 1865 ). It is thought that hatters suffered from the effects of mercury poisoning because of the fumes arising from the use of mercurous nitrate in the manufacture of felt hats. The March hare version refers to the way hares leap about during the breeding season.
(as) mad as a ˈhatter(informal) (of a person) crazyThe Mad Hatter was a character in Lewis Carroll’s Alice’s Adventures in Wonderland. Because of the chemicals used in hat-making, workers often suffered from mercury poisoning, which can cause loss of memory and damage to the nervous system.
mad as a hatter
Crazy. The standard explanation comes from the effect to the brain caused by mercury nitrate used by 18th- and 19th-century hatmakers. Another view holds that “mad” originally meant “poisonous” and “hatter” is a corruption of the Saxon word “atter,” the adder snake, the bite of which affects the brain. In any event, the Mad Hatter character in Lewis Carroll's Alice in Wonderland is a testimony to eccentricity bordering on madness.