moan vs rue

moan

verb
  • To complain; to grumble. 

  • To say in a moan, or with a moaning voice. 

  • To grieve. 

  • To make a moan or similar sound. 

noun
  • a low, mournful cry of pain, sorrow or pleasure 

rue

verb
  • To repent of or regret (some past action or event); to wish that a past action or event had not taken place. 

noun
  • Any of various perennial shrubs of the genus Ruta, especially the herb Ruta graveolens (common rue), formerly used in medicines. 

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