alarm vs pendulum

alarm

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

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

  • 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. 

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

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. 

pendulum

noun
  • A watch's guard-ring by which it is attached to a chain. 

  • Used to refer to the tendency of a situation to oscillate (between two extremes). 

  • A lamp, etc. suspended from a ceiling. 

  • A body suspended from a fixed support so that it swings freely back and forth under the influence of gravity, commonly used to regulate various devices such as clocks. 

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