Source : Webster's Revised Unabridged Dictionary (1913)

Ornamental \Or`na*men"tal\, a. [Cf. F. ornemental.]
   Serving to ornament; characterized by ornament; beautifying;
   embellishing.

         Some think it most ornamental to wear their bracelets
         on their wrists; others, about their ankles. --Sir T.
                                                  Browne.

Source : WordNet®

ornamental
     adj : serving an esthetic rather than a useful purpose; "cosmetic
           fenders on cars"; "the buildings were utilitarian
           rather than decorative" [syn: {cosmetic}, {decorative}]

ornamental
     n : any plant grown for its beauty or ornamental value