perplexity vs qualm

perplexity

noun
  • The state or quality of being perplexed; puzzled or confused. 

  • Something that perplexes. 

  • In information theory, a measurement of how well a probability distribution or model predicts a sample. 

qualm

noun
  • A feeling of apprehension, doubt, fear etc. 

  • A prick of the conscience; a moral scruple, a pang of guilt. 

  • A sudden sickly feeling; queasiness. 

verb
  • To have a sickly feeling. 

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