den vs phantom

den

noun
  • A squalid or wretched place; a haunt. 

  • 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. 

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

phantom

noun
  • A ghost or apparition. 

  • A placeholder for a pair of players when there are an odd number of pairs playing. 

  • Something apparently seen, heard, or sensed, but having no physical reality; an image that appears only in the mind; an illusion or delusion. 

  • A test object. A test phantom is an object that reproduces the characteristics of human tissue. 

adj
  • Illusive. 

  • Fictitious or nonexistent. 

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