From Longman Dictionary of Contemporary Englishornamentalor‧na‧men‧tal /ˌɔːnəˈmentl◂ $ ˌɔːr-/ adjective 
DECORATEdesigned to make something look attractive rather than to be used for a particular purpose ornamental gardens The pillars in the centre are purely ornamental.
DECORATEdesigned to make something look attractive rather than to be used for a particular purpose ornamental gardens The pillars in the centre are purely ornamental.Examples from the Corpus
ornamental• Miller quickly assimilated all that his father had himself taught him, within theory and practice of ornamental and kitchen gardening.• I passed through an ornamental entranceway with the street number in wrought iron arched across it in a rainbow shape.• Characteristic of the workshop are long ornamental extensions to the initials.• There was a tray on an ornamental garden table.• This is also the time to experiment with some unusual perennials and ornamental grasses you might not buy normally.• The elevator door on the first floor was ornamental iron lace.• an ornamental pond• A gardener comes in each week to trim the ornamental trees and bushes.• Prune fruit and other ornamental trees during winter dormancy.• Roses have structural as well as ornamental value in the garden.• ornamental vases 