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[mad] /mæd/
adjective, madder, maddest.
mentally disturbed; deranged; insane; demented.
enraged; greatly provoked or irritated; angry.
  1. abnormally furious; ferocious:
    a mad bull.
  2. affected with rabies; rabid:
    a mad dog.
extremely foolish or unwise; imprudent; irrational:
a mad scheme to invade France.
wildly excited or confused; frantic:
mad haste.
overcome by desire, eagerness, enthusiasm, etc.; excessively or uncontrollably fond; infatuated:
He's mad about the opera.
wildly lively and merry; enjoyably hilarious:
to have a mad time at the Mardi Gras.
(of wind, storms, etc.) furious in violence:
A mad gale swept across the channel.
an angry or ill-tempered period, mood, or spell:
The last time he had a mad on, it lasted for days.
verb (used with object), madded, madding.
Archaic. to make mad.
verb (used without object), madded, madding.
Archaic. to be, become, or act mad.
like mad, Informal. with great haste, impulsiveness, energy, or enthusiasm:
She ran like mad to catch the bus.
mad as a hatter, completely insane.
Origin of mad
before 900; Middle English mad (adj.), madden (intransitive v., derivative of the adj.); Old English gemǣd(e)d, past participle of *gemǣdan to make mad, akin to gemād mad, foolish; cognate with Old Saxon gemēd, Old High German gimeit foolish
Related forms
half-mad, adjective
half-madly, adverb
half-madness, noun
quasi-mad, adjective
quasi-madly, adverb
unmad, adjective
unmadded, adjective
1. lunatic, maniacal, crazed, crazy. 2. furious, exasperated, raging, wrathful, irate. 4. ill-advised; unsafe, dangerous, perilous. Mad, crazy, insane are used to characterize wildly impractical or foolish ideas, actions, etc. Mad suggests senselessness and excess: The scheme of buying the bridge was absolutely mad. In informal usage, crazy suggests recklessness and impracticality: a crazy young couple. Insane is used with some opprobrium to express unsoundness and possible harmfulness: The new traffic system is simply insane. 5. frenzied.
4. sensible, practical; sound, safe.
Usage note
Mad meaning “enraged, angry” has been used since 1300, and this sense is a very common one. Because some teachers and usage critics insist that the only correct meaning of mad is “mentally disturbed, insane,” mad is often replaced by angry in formal contexts: The president is angry at Congress for overriding his veto. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for half-mad
Contemporary Examples
Historical Examples
  • It was plain that the man was quivering with impatience and half-mad with excitement.

    The Black Bag Louis Joseph Vance
  • Tardeau, the half-mad French genius had explained it so logically.

    The Big Tomorrow Paul Lohrman
  • I was half-mad with pain and excitement then, and I wanted to save your life.

    Charge! George Manville Fenn
  • She hated herself and everybody; she was half-mad with fatigue and despondency.

    The Beloved Woman Kathleen Norris
  • He was starving and half-mad, that last letter to Catcott shows.

    Bristol Bells Emma Marshall
  • half-mad with mental agony, Myra repulsed her with a bitter laugh.

    Witness to the Deed George Manville Fenn
  • No; only that he was half-mad with joy, and when he kissed me and said good-night—you remember?

    Witness to the Deed George Manville Fenn
British Dictionary definitions for half-mad


not entirely sane
extremely upset or distracted: half-mad with fear


noun acronym (US)
mutual assured destruction: a theory of nuclear deterrence whereby each side in a conflict has the capacity to destroy the other in retaliation for a nuclear attack


adjective madder, maddest
mentally deranged; insane
senseless; foolish: a mad idea
(often foll by at) (informal) angry; resentful
foll by about, on, or over; often postpositive. wildly enthusiastic (about) or fond (of): mad about football, football-mad
extremely excited or confused; frantic: a mad rush
temporarily overpowered by violent reactions, emotions, etc: mad with grief
(of animals)
  1. unusually ferocious: a mad buffalo
  2. afflicted with rabies
(informal) like mad, with great energy, enthusiasm, or haste; wildly
mad as a hatter, crazily eccentric
verb mads, madding, madded
(archaic) to make or become mad; act or cause to act as if mad
Derived Forms
maddish, adjective
Word Origin
Old English gemǣded, past participle of gemǣdan to render insane; related to gemād insane, and to Old High German gimeit silly, crazy, Old Norse meitha to hurt, damage
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for half-mad



late 13c., from Old English gemædde (plural) "out of one's mind" (usually implying also violent excitement), also "foolish, extremely stupid," earlier gemæded "rendered insane," past participle of a lost verb *gemædan "to make insane or foolish," from Proto-Germanic *ga-maid-jan, demonstrative form of *ga-maid-az "changed (for the worse), abnormal" (cf. Old Saxon gimed "foolish," Old High German gimeit "foolish, vain, boastful," Gothic gamaiþs "crippled, wounded," Old Norse meiða "to hurt, maim"), from intensive prefix *ga- + PIE *moito-, past participle of root *mei- "to change" (cf. Latin mutare "to change," mutuus "done in exchange," migrare "to change one's place of residence;" see mutable).

Emerged in Middle English to replace the more usual Old English word, wod (see wood (adj.)). Sense of "beside oneself with excitement or enthusiasm" is from early 14c. Meaning "beside oneself with anger" is attested from early 14c., but deplored by Rev. John Witherspoon (1781) as an Americanism. It now competes in American English with angry for this sense. Of animals, "affected with rabies," from late 13c. Phrase mad as a March hare is attested from 1520s, via notion of breeding season; mad as a hatter is from 1829 as "demented," 1837 as "enraged," according to a modern theory supposedly from erratic behavior caused by prolonged exposure to poison mercuric nitrate, used in making felt hats. For mad as a wet hen see hen. Mad money is attested from 1922; mad scientist is from 1891.



late 14c., from mad (adj.).

Online Etymology Dictionary, © 2010 Douglas Harper
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half-mad in Medicine

mad (mād)

  1. Angry; resentful.

  2. Suffering from a disorder of the mind; insane.

  3. Affected by rabies; rabid.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Slang definitions & phrases for half-mad



  1. Angry (1400s+)
  2. Excellent; exciting; crazy (1950s+ Bop & cool talk)

Related Terms

like mad

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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Idioms and Phrases with half-mad
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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