disability vs efficacy

disability

noun
  • An inability imposed on a person by society's failure to accommodate their physical or mental differences from others, as opposed to impairment. 

  • A mental condition causing a difficulty with an intellectual task. 

  • Want of legal qualification to do a thing; legal incapacity or incompetency. 

  • Regular payments received by a disabled person, usually from the state 

  • State of being disabled; deprivation or want of ability; absence of competent physical, intellectual, or moral power, means, fitness, and the like. 

efficacy

noun
  • Ability to produce a desired effect under ideal testing conditions. 

  • Degree of ability to produce a desired effect; effectiveness. 

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