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

Class VI. Words Relating to the Sentient and Moral Powers
Section II. Personal Affections
2. Discriminative Affections

849. Simplicity.

   NOUN:SIMPLICITY; plainness, homeliness; undress, nudity, beauty unadorned; chasteness, chastity, restraint, severity, naturalness, unaffectedness.
   VERB:BE SIMPLE &c. adj.
  RENDER SIMPLE &c. adj.; simplify, reduce to simplicity, strip of ornament, chasten, restrain.
   ADJECTIVE:SIMPLE, plain, homelike, homish, homely, homespun [fig.], ordinary, household.
  unaffected, natural, native; inartificial (artless) [See Artlessness]; free from -affectation, – ornament; simplex munditiis [Horace]; sans façon [F.], en déshabillé [F.].
  chaste, inornate, severe.
  UNADORNED, unornamented, undecked, ungarnished, unarranged, untrimmed, unvarnished.
  bald, flat, blank, dull.
  SIMPLE-MINDED, childish, credulous [See Credulity].
  1. Veritatis simplex oratio est.
  2. Nothing is more simple than greatness; indeed, to be simple is to be great.—Emerson