gravity vs laughter

gravity

noun
  • The lowness of a note. 

  • The state or condition of being grave; seriousness. 

  • Specific gravity. 

  • The state or condition of having weight; weight; heaviness. 

  • Gravitation, the universal force exercised by two bodies onto each other. 

  • The force at the Earth's surface, of the attraction by the Earth's masses, and the centrifugal pseudo-force caused by the Earth's rotation, resulting from gravitation. 

laughter

noun
  • A movement (usually involuntary) of the muscles of the laughing face, particularly of the lips, and of the whole body, with a peculiar expression of the eyes, indicating merriment, satisfaction or derision, and usually attended by a sonorous and interrupted expulsion of air from the lungs. 

  • The sound of laughing, produced by air so expelled; any similar sound. 

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