attention deficit hyperactivity disorder vs stiffness

attention deficit hyperactivity disorder

noun
  • A developmental disorder in which a person has a persistent pattern of impulsiveness and inattention, with or without a component of hyperactivity. 

stiffness

noun
  • inelegance; a lack of relaxedness. 

  • rigidity or a measure of rigidity. 

  • inflexibility or a measure of inflexibility. 

  • muscular tension due to unaccustomed or excessive exercise or work; soreness. 

How often have the words attention deficit hyperactivity disorder and stiffness occurred in a corpus of books? (source: Google Ngram Viewer )