horse chestnut vs ruby

horse chestnut

noun
  • The large nutlike seed of these trees. 

  • Any of several tree species of genus Aesculus, especially Aesculus hippocastanum, common in temperate northern hemisphere. 

ruby

noun
  • A ruby hummer, a South American hummingbird, Clytolaema rubricauda. 

  • A deep red colour. 

  • A red bird-of-paradise, Paradisaea rubra. 

  • A pronunciation guide written above or beside Chinese or Japanese characters. 

  • A clear, deep, red variety of corundum, valued as a precious stone. 

  • The tincture red or gules. 

verb
  • To make red; to redden. 

adj
  • Of a deep red colour. 

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