fir vs pine nut

fir

noun
  • Any pinaceous conifer of related genera, especially a Douglas fir (Pseudotsuga) or a Scots pine (Pinus sylvestris). 

  • A conifer of the genus Abies. 

  • Wood of such trees. 

pine nut

noun
  • The edible seed of any of several species of evergreen pine, especially Pinus pinea, Pinus cembra, and Pinus cembroides. 

  • The flavor that results from mixing pineapple and coconut. 

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