alarm vs apprehension

alarm

noun
  • Sudden surprise with fear or terror excited by apprehension of danger; in the military use, commonly, sudden apprehension of being attacked by surprise. 

  • An instance of an alarm ringing, beeping or clanging, to give a noise signal at a certain time. 

  • A mechanical device for awaking people, or rousing their attention. 

  • A sudden attack; disturbance. 

  • Any sound or information intended to give notice of approaching danger; a warning sound to arouse attention; a warning of danger. 

  • A summons to arms, as on the approach of an enemy. 

verb
  • To give (someone) notice of approaching danger 

  • To rouse to vigilance and action; to put on the alert. 

  • To surprise with apprehension of danger; to fill with anxiety in regard to threatening evil; to excite with sudden fear. 

  • To call to arms for defense 

  • To keep in excitement; to disturb. 

apprehension

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

  • Opinion; conception; sentiment; idea. 

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

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

  • 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 alarm and apprehension occurred in a corpus of books? (source: Google Ngram Viewer )