palpitation vs tremor

palpitation

noun
  • An abnormal beating of the heart that may be perceived by the patient, a result of excitement, exertion, or illness. 

tremor

noun
  • A rhythmic, uncontrollable shaking of all or part of the body due to partial muscle contractions. 

  • An earthquake. 

  • A shake, quiver, or vibration. 

verb
  • To shake or quiver excessively and rapidly or involuntarily; to tremble. 

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