impediment vs stimulus

impediment

noun
  • Baggage, especially that of an army; impedimenta. 

  • A disability, especially one affecting the hearing or speech. 

  • A hindrance; that which impedes or obstructs progress. 

stimulus

noun
  • A sting on the body of a plant or insect. 

  • Something external that elicits or influences a physiological or psychological activity or response, or that affects any of the sensory apparatuses. 

  • An external phenomenon that has an influence on a system, by triggering or modifying an internal phenomenon; for example, a spur or incentive that drives a person to take action or change behaviour. 

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