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

483. Underestimation.

   NOUN:UNDERESTIMATION; depreciation (detraction) [See Detraction]; pessimism; self-detraction, self-depreciation; undervaluation, miosis, litotes [rhet.]; undervaluing &c. v.; modesty [See Modesty].
  PESSIMIST, depreciator, knocker [slang], crape-hanger [slang].
   VERB:UNDERRATE, underestimate, undervalue, underreckon; depreciate; disparage (detract) [See Detraction]; not do justice to; misprize, disprize; ridicule [See Ridicule]; pessimize; slight (despise) [See Contempt]; neglect [See Neglect]; slur over.
  make -light, – little, – nothing, – no account- of; belittle, knock [slang], slam [slang], run down [colloq.], minimize, think nothing of; set no store by, set at naught; shake off like water from a duck’s back, shake off as dewdrops from the lion’s mane.
   ADJECTIVE:DEPRECIATING &c. v.; depreciative, depreciatory.
  DEPRECIATED &c. v.; unappreciated, unvalued, unprized.
  1. All pessimism has a secret optimism for its object.—Chesterton
  2. Pessimist—a man who thinks everybody as nasty as himself and hates them for it.—Shaw