never-say-die vs unsinkable

never-say-die

adj
  • That does not give up in despair; indomitable. 

unsinkable

adj
  • That cannot be overcome or defeated. 

  • A piece of faeces that floats. 

  • Of a ship: that cannot be sunk. 

How often have the words never-say-die and unsinkable occurred in a corpus of books? (source: Google Ngram Viewer )