conceal vs secrete

conceal

verb
  • To hide something from view or from public knowledge, to try to keep something secret. 

secrete

verb
  • To conceal. 

  • To extract a substance from blood, sap, or similar to produce and emit waste for excretion or for the fulfilling of a physiological function. 

  • To exude or yield. 

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