convulse vs didder

convulse

verb
  • To violently shake or agitate. 

  • To suffer violent involuntary contraction of the muscles, producing contortions of the body or limbs. 

  • To create great laughter. 

didder

verb
  • To rattle or shiver. 

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