let-down vs loyalty

let-down

noun
  • A disappointment or anticlimax. 

  • The clearance of an aircraft to descend through clouds to clear air below, or the process of granting such a clearance. 

  • The neurohormonal release of milk in dairy cows or in breastfeeding human mothers. 

loyalty

noun
  • Faithfulness or devotion to some person, cause or nation. 

  • The state of being loyal; fidelity. 

How often have the words let-down and loyalty occurred in a corpus of books? (source: Google Ngram Viewer )