rock hard vs stony

rock hard

adj
  • As tough, hard, or inflexible as a piece of rock. 

  • With strongly held beliefs and opinions, deep conviction. 

  • With muscles developed and toned to a high degree, especially the muscles of the abdomen. 

  • Having a very fully erect and stiff penis 

stony

adj
  • As hard as stone. 

  • Of an action or expression such as a look, showing no warmth of emotion. 

  • Containing or made up of stones. 

  • Of a person, lacking warmth and emotion. 

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