pomelo vs pompelmos

pomelo

noun
  • The tree which produces this fruit. 

  • the grapefruit. 

  • The large fruit of the Citrus maxima (syn. C. grandis), native to South Asia and Southeast Asia, with a thick green or yellow rind, a thick white pith, and semi-sweet translucent pale flesh. 

pompelmos

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