solitary vs unique

solitary

adj
  • Not associated with others of the same kind. 

  • Performed, passed, or endured alone 

  • Living or being by oneself; alone; having no companion present 

  • Not much visited or frequented; remote from society 

  • Single; individual; sole. 

  • gloomy; dismal, because of not being inhabited. 

  • Not inhabited or occupied; without signs of inhabitants or occupation; desolate; deserted 

noun
  • One who lives alone, or in solitude; an anchorite, hermit or recluse. 

  • Solitary confinement. 

  • The state of being solitary; solitude 

unique

adj
  • Being the only one of its kind; unequaled, unparalleled or unmatched. 

  • Of a rare quality, unusual. 

  • Of a feature, such that only one holder has it. 

  • Particular, characteristic. 

noun
  • A thing without a like; something unequalled or unparallelled; one of a kind. 

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