coward vs pigeon-livered

coward

adj

  • Cowardly. 

  • Borne in the escutcheon with his tail doubled between his legs. 

noun

  • A person who lacks courage. 

pigeon-livered

adj

  • cowardly 

How often have the words coward and pigeon-livered occurred in a corpus of books? (source: Google Ngram Viewer )