Definition of "madness"

madness

/ˈmad.nəs/

noun
countable and uncountable, plural madnesses
1. The state of being mad; insanity; mental disease.
  Quotations
  Though this be madneſſe, / Yet there is Method in 't: […]
  c. 1599–1602 (date written), William Shakespeare, “The Tragedie of Hamlet, Prince of Denmarke”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene ii], page 261, column 2
  Shepard: What's wrong with your assistant?Dr. Warren: Manuel has a brilliant mind, but he's always been a bit... unstable. Genius and madness are two sides of the same coin.Dr. Manuel: Is it madness to see the future? To see the destruction rushing towards us? To understand there is no escape? No hope? No, I am not mad. I'm the only sane one left!Dr. Warren: I gave him an extra dose of his meds after the attack.
  2008, BioWare, Mass Effect, Redwood City: Electronic Arts, PC, scene: Eden Prime
2. The state of being angry.
3. rash folly