Dic: Synonyms: strength, power, might, energy, force

These nouns denote the capacity to act or work effectively.

• Strength refers especially to physical, mental, or moral robustness or vigor:
  … "enough work to do, and strength enough to do the work" (Rudyard Kipling).
  
  
• Power is the ability to do something and especially to produce an effect:
  … "I do not think the United States would come to an end if we lost our power to declare an Act of Congress void" (Oliver Wendell Holmes, Jr.)
  
  
• Might often implies abundant or extraordinary power:
  … "He could defend the island against the whole might of the German Air Force" (Winston S. Churchill).
  
  
• Energy refers especially to a latent source of power:
  … "The same energy of character which renders a man a daring villain would have rendered him useful to society, had that society been well organized" (Mary Wollstonecraft).
  
  
• Force is the application of power or strength:
  … "the overthrow of our institutions by force and violence" (Charles Evans Hughes).

.... The American Heritage