mad as a hatter


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*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

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

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