placation vs waning

placation

noun
  • A process or act of placating; appeasement or an expression of appeasement. 

waning

noun
  • The fact or act of becoming less or less intense or present; fading. 

  • The fact or act of becoming smaller. 

adj
  • Becoming weaker or smaller. 

  • Of the lunar phase: as it shrinks when viewed from the Earth. 

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