/mad/ , adj., madder, maddest , n. , v. , madded, madding .
adj.
1. mentally disturbed; deranged; insane; demented.
2. enraged; greatly provoked or irritated; angry.
3. (of animals)
a. abnormally furious; ferocious: a mad bull.
b. affected with rabies; rabid: a mad dog.
4. extremely foolish or unwise; imprudent; irrational: a mad scheme to invade France.
5. wildly excited or confused: frantic: mad haste.
6. overcome by desire, eagerness, enthusiasm, etc.; excessively or uncontrollably fond; infatuated: He's mad about the opera.
7. wildly gay or merry; enjoyably hilarious: to have a mad time at the Mardi Gras.
8. (of wind, storms, etc.) furious in violence: A mad gale swept across the channel.
9. like mad , Informal. with great haste, impulsiveness, energy, or enthusiasm: She ran like mad to catch the bus.
10. mad as a hatter , completely insane.
n.
11. an angry or ill-tempered period, mood, or spell: The last time he had a mad on, it lasted for days.
v.t.
12. Archaic. to make mad.
v.i.
13. Archaic. to be, become, or act mad.
[ bef. 900; ME mad (adj.), madden (intrans. v., deriv. of the adj.); OE gemaed ( e ) d, ptp. of * gemaedan to make mad, akin to gemad mad, foolish; c. OS gemed, OHG gimeit foolish ]
Syn. 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.
Ant. 4. sensible, practical; sound, safe.
Usage . 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.