convulsion vs hippus

convulsion

noun
  • An intense, paroxysmal, involuntary muscular contraction. 

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

  • Violent turmoil. 

hippus

noun
  • pupillary athetosis; spasmodic dilation and contraction of the pupil between the sphincter and dilator muscles. 

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