impetrate vs sifflicate

impetrate

verb
  • To obtain by asking; to procure upon request. 

  • To ask for; to demand. 

sifflicate

verb
  • To supplicate, petition, importune, or wheedle 

  • To suggest 

  • To criticise 

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