lilac vs orchid

lilac

adj
  • Having a pale purple colour. 

noun
  • A flower of the lilac shrub. 

  • A pale purple color, the color of some lilac flowers. 

  • A large shrub of the genus Syringa, especially Syringa vulgaris, bearing white, pale-pink, or purple flowers. 

orchid

adj
  • having a light purple colour. 

noun
  • A light bluish-red, violet-red or purple colour. 

  • A plant of the orchid family (Orchidaceae), bearing unusually-shaped flowers of beautiful colours. 

How often have the words lilac and orchid occurred in a corpus of books? (source: Google Ngram Viewer )