The Collaborative International Dictionary of English v.0.48:

Madness \Mad"ness\, n. [From Mad, a.]
   1. The condition of being mad; insanity; lunacy.
      [1913 Webster]

   2. Frenzy; ungovernable rage.
      [1913 Webster]

   3. Extreme folly.
      [1913 Webster]

   Syn: Insanity; distraction; derangement; craziness; lunacy;
        mania; frenzy; franticness; rage; aberration;
        alienation; monomania. See Insanity.
        [1913 Webster]

WordNet (r) 3.0 (2006):

madness
    n 1: obsolete terms for legal insanity [syn: lunacy,
         madness, insaneness]
    2: an acute viral disease of the nervous system of warm-blooded
       animals (usually transmitted by the bite of a rabid animal);
       rabies is fatal if the virus reaches the brain [syn:
       rabies, hydrophobia, lyssa, madness]
    3: a feeling of intense anger; "hell hath no fury like a woman
       scorned"; "his face turned red with rage" [syn: fury,
       rage, madness]
    4: the quality of being rash and foolish; "trying to drive
       through a blizzard is the height of folly"; "adjusting to an
       insane society is total foolishness" [syn: folly,
       foolishness, craziness, madness]
    5: unrestrained excitement or enthusiasm; "poetry is a sort of
       divine madness" [syn: madness, rabidity, rabidness]

Moby Thesaurus II by Grady Ward, 1.0:

246 Moby Thesaurus words for "madness":
   African lethargy, Asiatic cholera, Chagres fever, German measles,
   Haverhill fever, abandon, aberration, abnormality,
   acute articular rheumatism, ague, alienation, alkali disease,
   amebiasis, amebic dysentery, anthrax, asininity,
   bacillary dysentery, bastard measles, battiness, black death,
   black fever, blackwater fever, brain damage, brainlessness,
   brainsickness, breakbone fever, brucellosis, bubonic plague,
   buffoonery, cachectic fever, cerebral rheumatism, chicken pox,
   cholera, clouded mind, clownishness, cowpox, crackpottedness,
   crankiness, craze, craziness, daffiness, daftness, dandy fever,
   deer fly fever, delirium, dementedness, dementia, dengue,
   dengue fever, derangement, desipience, diphtheria, disorientation,
   distraction, dumdum fever, dysentery, eccentricity, ecstasy,
   elephantiasis, encephalitis lethargica, enteric fever, erysipelas,
   famine fever, fatuity, fatuousness, fire and fury, five-day fever,
   flu, folie, folly, foolery, foolheadedness, foolishness, frambesia,
   frenzy, frivolity, frivolousness, furor, furore, fury, futility,
   giddiness, glandular fever, goofiness, grippe, hansenosis,
   hepatitis, herpes, herpes simplex, herpes zoster, histoplasmosis,
   hookworm, hydrophobia, hysteria, idiocy, illogic, illogicality,
   illogicalness, imbecility, impracticality, inanity, ineptitude,
   infantile paralysis, infectious mononucleosis,
   inflammatory rheumatism, influenza, insaneness, insanity,
   intoxication, irrationality, jail fever, jungle rot, kala azar,
   kissing disease, lepra, leprosy, leptospirosis, loa loa, loaiasis,
   lockjaw, loss of mind, loss of reason, lunacy, malaria,
   malarial fever, mania, marsh fever, measles, meningitis,
   mental deficiency, mental derangement, mental disease,
   mental disorder, mental disturbance, mental illness,
   mental instability, mental sickness, milzbrand, mind overthrown,
   mindlessness, mindsickness, mumps, niaiserie, nonsense, nugacity,
   nuttiness, oddness, orgasm, orgy, ornithosis, osteomyelitis,
   paratyphoid fever, parotitis, parrot fever, passion, pertussis,
   pixilation, pneumonia, pointlessness, polio, poliomyelitis,
   polyarthritis rheumatism, ponos, possession, preposterousness,
   psittacosis, psychopathy, psychosis, queerness, rabbit fever,
   rabidness, rabies, rage, rapture, rat-bite fever, ravishment,
   reasonlessness, relapsing fever, rheumatic fever, rickettsialpox,
   ridiculousness, ringworm, rubella, rubeola, sappiness, scarlatina,
   scarlet fever, schistosomiasis, screwiness, senselessness,
   septic sore throat, shattered mind, shingles, sick mind, sickness,
   silliness, sleeping sickness, sleepy sickness, smallpox,
   snail fever, splenic fever, spotted fever, strangeness,
   strep throat, stupidity, swamp fever, tearing passion, tetanus,
   thoughtlessness, thrush, tinea, towering rage, transport,
   trench fever, trench mouth, triflingness, triviality, tuberculosis,
   tularemia, typhoid, typhoid fever, typhus, typhus fever, unbalance,
   unbalanced mind, undulant fever, unsaneness, unsound mind,
   unsoundness, unsoundness of mind, vaccinia, varicella, variola,
   venereal disease, viral dysentery, wackiness, weirdness,
   whooping cough, witlessness, yaws, yellow fever, yellow jack,
   zaniness, zanyism, zona, zoster



Easton's 1897 Bible Dictionary:

Madness
   This word is used in its proper sense in Deut. 28:34, John
   10:20, 1 Cor. 14:23. It also denotes a reckless state of mind
   arising from various causes, as over-study (Eccl. 1:17; 2:12),
   blind rage (Luke 6:11), or a depraved temper (Eccl. 7:25; 9:3; 2
   Pet. 2:16). David feigned madness (1 Sam. 21:13) at Gath because
   he "was sore afraid of Achish."