jetty vs molehead

jetty

noun
  • A structure of wood or stone extended into the sea to influence the current or tide, or to protect a harbor or beach. 

  • A part of a building that jets or projects beyond the rest, and overhangs the wall below. 

  • A wharf or dock extending from the shore. 

molehead

noun
  • A stone bulwark forming a haven or harbour; a breakwater. 

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