weak-willed vs yellow-bellied

weak-willed

adj
  • irresolute, indecisive 

  • easily swayed 

yellow-bellied

adj
  • Uncourageous, cowardly. 

  • Of an animal or reptile having a yellow underside or belly. 

How often have the words weak-willed and yellow-bellied occurred in a corpus of books? (source: Google Ngram Viewer )