ardency vs urge to merge

ardency

noun
  • Intensity of feelings. 

  • Intensity of devotion. 

  • Intensity of light. 

  • Intensity of heat or burning. 

urge to merge

noun
  • A strong desire to form intense emotional connections, stereotypically associated with lesbians. 

How often have the words ardency and urge to merge occurred in a corpus of books? (source: Google Ngram Viewer )