agitation vs apprehension

agitation

noun
  • The act of agitating, or the state of being agitated; the state of being disrupted with violence, or with irregular action; commotion. 

  • A disturbance of personal tranquillity; disturbance of someone's peace of mind. 

  • Excitement of public feeling by discussion, appeals, etc. 

apprehension

noun
  • The physical act of seizing or taking hold of (something); seizing. 

  • Opinion; conception; sentiment; idea. 

  • Anticipation, especially of unfavorable things such as dread or fear or the prospect of something unpleasant in the future. 

  • The faculty by which ideas are conceived or by which perceptions are grasped; understanding. 

  • Perception; the act of understanding using one's intellect without affirming, denying, or passing any judgment 

  • The act of seizing or taking by legal process; arrest. 

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