den vs enter

den

verb
  • To ensconce or hide oneself in (or as in) a den. 

noun
  • Synonym of fort (“structure improvised from furniture, etc. for playing games.”) 

  • A comfortable room not used for formal entertaining. 

  • A group of Cub Scouts of the same age who work on projects together. 

  • A small cavern or hollow place in the side of a hill, or among rocks; especially, a cave used by a wild animal for shelter or concealment. 

  • A squalid or wretched place; a haunt. 

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. 

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