enter vs retreat

enter

verb
  • To go or come into an enclosed or partially enclosed space. 

  • To become effective; to come into effect. 

  • To go or come into (a state or profession). 

  • To become a party to an agreement, treaty, etc. 

  • To cause to go (into), or to be received (into); to put in; to insert; to cause to be admitted. 

  • To place in regular form before the court, usually in writing; to put upon record in proper from and order 

  • To go into or upon, as lands, and take actual possession of them. 

  • To deposit for copyright the title or description of (a book, picture, map, etc.). 

  • To type (something) into a computer; to input. 

  • To record (something) in an account, ledger, etc. 

  • To make report of (a vessel or its cargo) at the custom house; to submit a statement of (imported goods), with the original invoices, to the proper customs officer for estimating the duties. See entry. 

retreat

verb
  • To withdraw from a position, go back. 

  • To slope back. 

  • To withdraw military forces 

  • To shrink back due to generally warmer temperatures. 

  • a retreating forehead 

noun
  • A peaceful, quiet place affording privacy or security. 

  • The act of reversing direction and receding from a forward position. 

  • A bugle call or drumbeat signaling the lowering of the flag at sunset, as on a military base. 

  • A military ceremony to lower the flag. 

  • The move of a piece from a threatened position. 

  • A period of retirement, seclusion, or solitude. 

  • A period of meditation, prayer or study. 

  • The act of pulling back or withdrawing, as from something dangerous, or unpleasant. 

  • A signal for a military withdrawal. 

  • Withdrawal by military force from a dangerous position or from enemy attack. 

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