Source : Webster's Revised Unabridged Dictionary (1913)

Greenness \Green"ness\, n. [AS. gr[=e]nnes. See {Green.}]
   1. The quality of being green; viridity; verdancy; as, the
      greenness of grass, or of a meadow.

   2. Freshness; vigor; newness.

   3. Immaturity; unripeness; as, the greenness of fruit;
      inexperience; as, the greenness of youth.

Source : WordNet®

greenness
     n 1: lush greenness of flourishing vegetation [syn: {verdancy}, {verdure}]
     2: the state of not being ripe [ant: {ripeness}]
     3: the property of being green; resembling the color of growing
        grass [syn: {green}, {viridity}]