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adj. mad·der, mad·dest
1. Angry; resentful: was mad about the broken vase. See Synonyms at angry.
a. Mentally deranged: "afflicted with hypochondria, depression, and fear of going mad" (Carla Cantor).
b. Characteristic of mental derangement: mad laughter.
c. Temporarily or apparently deranged by violent sensations, emotions, or ideas: was mad with jealousy.
a. Lacking restraint or reason; foolish: I was mad to have hired her in the first place.
b. Feeling or showing strong liking or enthusiasm: mad about sports.
c. Marked by a lack of restraint, especially by extreme excitement, confusion, or agitation: a mad scramble for the bus.
4. Exhibiting uncharacteristic aggressiveness, especially as a result of rabies, spongiform encephalopathy, or another neurological disease. Used of animals: a mad dog; a mad cow.
a. Excellent; wonderful: It's really mad that they can come.
b. Abundant; great: mad respect.
tr. & intr.v. mad·ded, mad·ding, mads
To make or become mad; madden.
Extremely; very: This place is mad cool.
like mad Informal
1. Wildly; impetuously: drove like mad.
2. To an intense degree or great extent: worked like mad; snowing like mad.
mad as a hatter/March hare
Crazy; mentally deranged.
[Middle English, mentally deranged, rabid, angry, from Old English gemǣdde, past participle of *gemǣdan, to derange mentally, madden, from gemād, mentally deranged; see mei- in Indo-European roots.]
mutually assured destruction