Source : Webster's Revised Unabridged Dictionary (1913)

Simplicity \Sim*plic"i*ty\, n. [F. simplicit['e], L.
   simplicitas. See {Simple}.]
   1. The quality or state of being simple, 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; as, the simplicity of a machine.

   3. Artlessness of mind; freedom from cunning or duplicity;
      lack of acuteness and sagacity.

            Marquis Dorset, a man, for his harmless simplicity
            neither misliked nor much regarded.   --Hayward.

            In wit a man; simplicity a child.     --Pope.

   4. Freedom from artificial ornament, pretentious style, or
      luxury; plainness; as, simplicity of dress, of style, or
      of language; simplicity of diet; simplicity of life.

   5. Freedom from subtlety or abstruseness; clearness; as, the
      simplicity of a doctrine; the simplicity of an explanation
      or a demonstration.

   6. Weakness of intellect; silliness; folly.

            How long, ye simple ones, will ye love simplicity?
            and the scorners delight in their scorning? --Prov.
                                                  i. 22.

Source : WordNet®

simplicity
     n 1: the quality of being simple or uncompounded; "the simplicity
          of a crystal" [syn: {simpleness}] [ant: {complexity}]
     2: a lack of penetration or subtlety; "they took advantage of
        her simplicity" [syn: {simple mindedness}]
     3: absence of affectation or pretense
     4: freedom from difficulty or hardship or effort; "he rose
        through the ranks with apparent ease"; "they put it into
        containers for ease of transportation" [syn: {ease}, {easiness}]
        [ant: {difficulty}]
     5: lack of ornamentation; "the room was simply decorated with
        great restraint" [syn: {chasteness}, {restraint}]