Source : Webster's Revised Unabridged Dictionary (1913)

Singleness \Sin"gle*ness\, n.
   1. The quality or state of being single, or separate from all
      others; the opposite of doubleness, complication, or
      multiplicity.

   2. Freedom from duplicity, or secondary and selfish ends;
      purity of mind or purpose; simplicity; sincerity; as,
      singleness of purpose; singleness of heart.

Source : WordNet®

singleness
     n 1: without hypocrisy; "the singleness of his motives could not
          be questioned" [syn: {straightforwardness}]
     2: the quality of concentrating on one central objective; "his
        singleness of purpose"