phantom vs shadowing

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. 

shadowing

noun
  • A faint representation; an adumbration. 

  • Secretly or discreetly tracking or following someone, keeping under surveillance. 

  • The situation where an individual repeats speech immediately as they hear it (usually through earphones). 

  • The technique of copying ROM contents to RAM to allow for shorter access times. The ROM chip is then disabled while the initialized memory locations are switched in on the same block of addresses. 

  • The effect of being shadowed (in the sense of blocked), as from a light source or radio transmission. 

  • A work experience option where students learn about a job by walking through the work day as a shadow to a competent worker. 

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