entrench vs observe

entrench

verb
  • 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. 

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

observe

verb
  • To follow or obey the custom, practice, or rules (especially of a religion). 

  • To take note of and celebrate (a holiday or similar occurrence); to follow (a type of time or calendar reckoning). 

  • To notice or view, especially carefully or with attention to detail. 

  • To comment on something; to make an observation. 

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