grapefruit vs pampelmoes

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. 

pampelmoes

noun
  • Synonym of pomelo, as both a large fruit of Southeast Asia and as a catchall term for other related fruit such as the grapefruit. 

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