lament vs rue

lament

verb
  • To feel great sorrow or regret; to bewail. 

  • To express grief; to weep or wail; to mourn. 

noun
  • A song expressing grief. 

  • An expression of grief, suffering, sadness or regret. 

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 lament and rue occurred in a corpus of books? (source: Google Ngram Viewer )