convulsion vs shudder

convulsion

noun
  • An uncontrolled fit, as of laughter; a paroxysm. 

  • An intense, paroxysmal, involuntary muscular contraction. 

  • Violent turmoil. 

shudder

noun
  • A moment of almost pleasurable fear; a frisson. 

  • A shivering tremor, often from fear or horror. 

verb
  • To vibrate jerkily. 

  • To shake nervously, often from fear or horror. 

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