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

491. Ignorance.

   NOUN:IGNORANCE, nescience, tabula rasa [L.], illiteracy, unlearnedness, crass ignorance, ignorance crasse [F.]; unacquaintance; unconsciousness &c. adj.; darkness, blindness; incomprehension, inexperience, simplicity.
  sealed book, terra incognita [L.], virgin soil, unexplored ground; dark ages.
  unknown quantities; x, y, z.
  [IMPERFECT KNOWLEDGE] smattering, superficiality, half-learning, shallowness, sciolism, glimmering; bewilderment (uncertainty) [See Uncertainty]; incapacity.
  [AFFECTATION OF KNOWLEDGE] pedantry, charlatanry, charlatanism; Philistine, Philister [Ger.].
   VERB:BE IGNORANT &c. adj.; not know [See Knowledge]; know -not, – not what, – nothing of; have no -idea, – notion, – conception; not have the remotest idea; not know chalk from cheese; not know a B from a -bull’s foot, – battledore, – broomstick.
  ignore, be blind to; keep in ignorance (conceal) [See Concealment].
  see through a glass darkly; have a film over the eyes, have a glimmering &c. n.; wonder whether; not know what to make of (unintelligibility) [See Unintelligibility]; not pretend to say, not take upon oneself to say.
   ADJECTIVE:IGNORANT; nescient; unknowing, unaware, unacquainted, unapprized, unwitting, unweeting [obs.], unconscious; witless, weetless [obs.]; a stranger to; unconversant.
  UNINFORMED, uncultivated, unversed, uninstructed, untaught, uninitiated, untutored, unschooled, unscholarly, unguided, unenlightened; Philistine; behind the age.
  SHALLOW, superficial, green, rude, empty, half-learned, half-baked [colloq.], low-brow [slang]; illiterate; unread, uninformed, uneducated, unlearned, unlettered, unbookish; empty-headed; pedantic.
  IN THE DARK; benighted, belated; blinded, blindfold; hoodwinked; misinformed; au bout de son latin [F.], at the end of his tether, at fault; at sea (uncertain) [See Uncertainty]; caught tripping, caught napping.
  UNKNOWN, unapprehended, unexplained, unascertained, uninvestigated, unexplored, unheard of, unperceived; concealed [See Concealment]; novel.
   ADVERB:IGNORANTLY &c. adj.; unawares; for anything one knows, for aught one knows; not that one knows.
   INTERJECTION:God -, Heaven -, the Lord -, dear [dial.] -, nobody- knows!    QUOTATIONS:
  1. Ignorance never settles a question.—Disraeli
  2. Quantum animis erroris inest!—Ovid
  3. Small Latin and less Greek.—B. Jonson
  4. That unlettered, small-knowing soul.—Love’s Labor’s Lost
  5. There is no darkness but ignorance.—Twelfth Night
  6. A little learning is a dangerous thing.—Pope
  7. Only are reputed wise For saying nothing.—Merchant of Venice