nightmare vs vexation

nightmare

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

  • A very bad or frightening dream. 

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

verb
  • To have a nightmare. 

vexation

noun
  • The state of being vexed or irritated. 

  • The act of annoying, vexing, or irritating. 

  • Something that vexes or irritates. 

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