Dictionary

simplicity

Pronunciation

Noun

simplicity

The state or quality of being simple
1. The quality or state of being unmixed or uncompounded
  as, the simplicity of metals or of earths
2. The quality or state of being not complex, or of consisting of few parts
  the simplicity of a machine
3. Lack of sharpness of mind; lack of ability to think using complex ideas; stupidity
4. Lack of artificial ornament, pretentious style, or luxury; plainness
  simplicity of dress, of style, or of language
  simplicity of diet
  simplicity of life
5. Freedom from subtlety or abstruseness; clarity
  the simplicity of a doctrine
  the simplicity of an explanation or a demonstration
6. Freedom from complication; efficiency.
(archaic, rare) An act or instance of foolishness.
- 1603, Michel de Montaigne, chapter 31, in John Florio, transl., The Essayes, […], book II, printed at London: By Val[entine] Simmes for Edward Blount […], OCLC 946730821 ↗:
  speaking of the great simplicity we commit, in leaving yong children under the government and charge of their fathers and parents.