strange vs unknown

strange

adj
  • Unfamiliar, not yet part of one's experience. 

  • Outside of one's current relationship; unfamiliar. 

  • Not normal; odd, unusual, surprising, out of the ordinary. 

  • Having the quantum mechanical property of strangeness. 

  • Not belonging to one. 

  • Of an attractor: having a fractal structure. 

noun
  • Sex outside of one's current relationship. 

unknown

adj
  • Not known; unidentified; not well known. 

noun
  • A variable (usually x, y or z) whose value is to be found. 

  • A person of no identity; a nonentity 

  • Any thing, place, or situation about which nothing is known; an unknown fact or piece of information. 

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