Source : Webster's Revised Unabridged Dictionary (1913)

Naturalness \Nat"u*ral*ness\, n.
   The state or quality of being natural; conformity to nature.

Source : WordNet®

naturalness
     n 1: the quality of being natural or based on natural principles;
          "he accepted the naturalness of death"; "the spontaneous
          naturalness of his manner" [ant: {unnaturalness}]
     2: the quality of innocent naivete [syn: {artlessness}, {innocence},
         {ingenuousness}]