muscular vs rock hard

muscular

adj
  • Having large, well-developed muscles. 

  • Robust, strong. 

  • Full-bodied 

  • Of, relating to, or connected with muscles. 

  • Brawny, thewy, having strength. 

rock hard

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

  • With strongly held beliefs and opinions, deep conviction. 

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

  • Having a very fully erect and stiff penis 

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