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

Class IV. Words Relating to the Intellectual Faculties
Division (II) Communication of Ideas
Section III. Means of Communicating Ideas
Various Qualities of Style

571. Obscurity.

   NOUN:OBSCURITY (unintelligibility) [See Unintelligibility]; involution, crabbedness, confusion; hard words; ambiguity [See Equivocalness]; unintelligibility, unintelligibleness; vagueness [See Uncertainty], inexactness [See Error]; what d’ye call ’em (neologism) [See Neology]; darkness of meaning.
   ADJECTIVE:OBSCURE &c. n.; crabbed; involved, confused.
   QUOTATION:Full of sound and fury, Signifying nothing.—Macbeth