bitter orange vs grapefruit

bitter orange

noun
  • A citrus tree of the species Citrus limetta. 

  • The fruit of these species. 

  • A citrus tree of the species Citrus ×aurantium, also called Citrus aurantium. 

grapefruit

noun
  • The tree of the species Citrus paradisi, a hybrid of pomelo (Citrus maxima) and sweet orange. 

  • The large spherical tart fruit produced by this tree. 

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