intensity vs relaxation

intensity

noun
  • Time-averaged energy flux (the ratio of average power to the area through which the power "flows"); irradiance. 

  • Can mean any of radiant intensity, luminous intensity or irradiance. 

  • Synonym of radiance. 

  • The degree of strength. 

  • The quality of being intense. 

  • The severity of an earthquake in terms of its effects on the earth's surface, and buildings. The value depends on the distance from the epicentre, and is not to be confused with the magnitude. 

relaxation

noun
  • The transition of a nucleus, atom or molecule from a higher energy level to a lower one; the opposite of excitation 

  • The release following musical tension. 

  • A diminution of tone, tension, or firmness; specifically in pathology: a looseness; a diminution of the natural and healthy tone of parts. 

  • Remission of attention or application. 

  • The act of relaxing or the state of being relaxed; the opposite of stress or tension; the aim of recreation and leisure activities. 

  • Unbending; recreation; a state or occupation intended to give mental or bodily relief after effort. 

  • Remission or abatement of rigor. 

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