mara vs nightmare

mara

noun
  • A nightmare; a spectre or wraith-like creature in Germanic and particularly Scandinavian folklore; a female demon who torments people in sleep by crouching on their chests or stomachs, or by causing terrifying visions. 

  • Any malicious or evil spirit. 

  • Any caviid rodent of genus Dolichotis, common in the Patagonian steppes of Argentina. 

  • A type of god that prevents accomplishment or success. 

nightmare

noun
  • A very bad or frightening dream. 

  • Any bad, miserable, difficult or terrifying situation or experience that arouses anxiety, terror, agony or great displeasure. 

  • A feeling of extreme anxiety or suffocation experienced during sleep; Sleep paralysis. 

verb
  • To have a nightmare. 

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