Mawson, C.O.S., ed. (1870–1938). Roget’s International Thesaurus. 1922.

Class IV. Words Relating to the Intellectual Faculties
Division (I) Formation of Ideas
Section V. Results of Reasoning

503. Insanity.

   NOUN:INSANITY, lunacy; madness &c. adj., mania, rabies, furor, mental alienation, aberration, amentia, paranoia; dementation, dementia, demency [rare], morosis, idiocy; dementia a potu [L.], delirium tremens, D. T.’s, the horrors [colloq.]; phrenitis, frenzy, raving, incoherence, wandering, delirium, calenture of the brain, delusion, hallucination; lycanthropy; brain storm.
  DERANGEMENT; disordered -reason, – intellect; diseased -, unsound -, abnormal- mind; unsoundness.
  VERTIGO, dizziness, swimming, sunstroke, coup de soleil [F.], siriasis.
  ODDITY, eccentricity, twist, monomania; fanaticism, infatuation, craze; kleptomania, dipsomania; hypochondriasis (low spirits) [See Dejection]; melancholia, hysteria.
  screw -, tile -, slate- loose; bee in one’s bonnet, rats in the upper story, bats in the belfry, bee in the head [all colloq.].
  dotage (imbecility) [See Imbecility. Folly].
   VERB:BE or BECOME INSANE &c. adj.; lose one’s senses, – reason, – faculties, – wits; go mad, run mad; rave, dote, ramble, wander; drivel (be imbecile) [See Imbecility. Folly]; have a screw loose &c. n., have a devil; avoir le diable au corps [F.]; lose one’s head (be uncertain) [See Uncertainty].
  DERANGE; render or drive mad &c. adj.; madden, dementate [rare], addle the wits, derange the head, infatuate, befool; turn the brain, turn one’s head.
   ADJECTIVE:INSANE, mad, lunatic; crazy, crazed, aliéné [F.], non compos mentis [L.], not right, dement [rare], dementate, cracked [colloq.], touched; bereft of reason; all- possessed, unhinged, unsettled in one’s mind; insensate, reasonless, beside oneself, demented, maniacal, daft; frenzied, frenetic or frenetical; possessed, – with a devil; deranged, far gone, maddened, moonstruck; shatterpated, shatterbrained; madbrained, scatterbrained, crack-brained; off one’s head.
  Corybantic, dithyrambic; rabid, giddy, vertiginous, wild; haggard, mazed; flighty; distracted, distraught; bewildered (uncertain) [See Uncertainty].
  mad as a -March hare, – hatter; of unsound mind &c. n.; touched -, wrong -, not right- in one’s -head, – mind, – wits, – upper story [colloq.]; out of one’s -mind, – senses, – wits; not in one’s right mind; nutty [slang].
  ODD, fanatical, infatuated, eccentric; hypochondriac, hyppish [rare], hipped or hypped [colloq.], hippish [colloq.].
  DELIRIOUS, light-headed, incoherent, rambling, doting, wandering; frantic, raving, stark mad, stark staring mad.
  IMBECILE, silly, [See Imbecility. Folly].
   ADVERB:like one possessed.
  1. The mind having lost its balance; the reason under a cloud.
  2. Tête exaltée; tête montée; ira furor brevis est; omnes stultos insanire.—Horace
  3. Great wits are sure to madness near allied.—Dryden
  4. Moping melancholy and moon-struck madness.—Milton
  5. And moody madness laughing wild Amid severest woe.—Gray
  6. Though this be madness, yet there is method in’t.—Hamlet
  7. No excellent soul is exempt from a mixture of madness.—Aristotle
  8. Fetter strong madness in a silken thread.—Much Ado About Nothing
  9. That he is mad, ’tis true, ‘tis true, ’tis pity; And pity ’tis ’tis true.—Hamlet
  10. We are not ourselves When nature, being oppress’d, commands the mind To suffer with the body.—King Lear