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Related to hatter: hater, Alice

(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.
See also: hatter, mad

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.
See also: hatter, mad
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

*mad as a hatter

 and *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.
See also: hatter, mad
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

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.
See also: hatter, mad
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

mad as a hatter

mainly 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'.
See also: hatter, mad
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012

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.
See also: hatter, mad
Farlex Partner Idioms Dictionary © Farlex 2017

(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.
See also: hatter, mad
Farlex Partner Idioms Dictionary © Farlex 2017

mad as a hatter

Crazy. Although many readers associate mad hatter with Alice’s tea party in Wonderland, attended by both a March Hare and a Hatter, the term is considerably older and is thought to come from the fact that the chemicals used in making felt hats could produce the symptoms of Saint Vitus’ dance or other nervous tremors. In literature, references occur in Thomas Haliburton’s The Clockmaker (1837) and Thackeray’s Pendennis (1850), both predating Lewis Carroll’s Alice’s Adventures in Wonderland (1865). The synonym mad as a March hare, incidentally, which dates from Chaucer’s time, is virtually obsolete.
See also: hatter, mad
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer

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.
See also: hatter, mad
Endangered Phrases by Steven D. Price Copyright © 2011 by Steven D. Price
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References in periodicals archive ?
During his career, Hatter has also served as director, senior manager at Citigroup Global Wealth Advisory (NYSE: C) and as senior vice president and regional manager at Merrill Lynch Capital, Heller Financial, and Fleet Capital Corporation.
While dining at The Mad Hatter you are welcome to browse the charming gift shop, walk around the beautiful historic grounds or stroll down the winding walk path to get a closer view of the Rum River.
"Hatter is a leader at heart and can manage at both strategic and tactical levels," said Mark Pougnet, COO and CFOof Wazee Digital.
For more information, see the shop's Twitter feed @ LONDISPENNYLANE Mad Hatter's beers have included Liverpool Tart, a Vasily Petrenko ale and a cucumber and yoghurt ale, Tzatziki Sour.
They will serve as the henchmen of the Mad Hatter as he goes in search for Alice.
But Bobin seems out of his depth as he tips his Mad Hatter's hat to distracting wordplay and smug in-jokes.
Also look out for a very special treat at noon with a magical visit from the Mad Hatter himself, Jasper Blakeley.
Library director Louisa Yates said: "Our Mad Hatter's Tea Party will pay homage to the weird and wonderful classic novel, while showcasing the beautiful library."
The British people, depicted as Alice, look on in amazement at the crazy antics of our politicians and councillors who are represented by the Mad Hatter. After all, the Mad Hatter fusses around, talks a lot and makes a cup of tea - just like our LibLabCon team.
THE HERBERT Art Gallery became a Wonderland of its very own as Alice and friends popped in for a Mad Hatter's tea party.
The theme started this week with a Mad Hatter's Tea Party supplied by the parents.
London, March 8 ( ANI ): Coleen and Wayne Rooney's son Kai looked adorable as he dressed as the Mad Hatter to celebrate World Book Day on Thursday.
The Mad Hatter's themed tea party at the store, at the Great Northern Retail Park, raised the cash for The Forget Me Not Children's Hospice, Brackenhall.
But Donald Hatter, founder of Inner-Wipes, Lincroft, NJ, says he's about to change all that with the creation of a wipes dispenser that fits easily on standard toilet paper rolls.