citron vs gamboge

citron

adj
  • Of a greenish yellow colour. 

noun
  • The fruit of a citron tree. 

  • A greenish yellow colour. 

  • The candied rind of the citron fruit. 

  • A small citrus tree, Citrus medica. 

gamboge

adj
  • Of a deep yellow colour. 

noun
  • The resin of the gamboge tree; a preparation of the resin used as a pigment or for medicinal purposes. 

  • One of several species of trees of the genus Garcinia found in South and Southeastern Asia, especially Garcinia xanthochymus. 

  • A deep yellow colour. 

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