entrench vs penetrate

entrench

verb
  • To cut in; to furrow; to make trenches in or upon. 

  • To surround or provide with a trench, especially for defense; to dig in. 

  • To establish a substantial position in business, politics, etc. 

  • To dig or excavate a trench; to trench. 

  • To invade; to encroach; to infringe or trespass; to enter on, and take possession of, that which belongs to another; usually followed by on or upon. 

  • To become completely absorbed in and fully accept one's beliefs, even in the face of evidence against it and refusing to be reasoned with. 

penetrate

verb
  • To enter into; to make way into the interior of; to pierce. 

  • To achieve understanding of, despite some obstacle; to comprehend; to understand. 

  • To move a piece past the defending pieces of one's opponent. 

  • To affect profoundly through the senses or feelings; to move deeply. 

  • To insert the penis into an opening, such as a vagina, mouth or anus. 

  • To infiltrate an enemy to gather intelligence. 

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