unknown

Adjective

• not known before
  • used many strange words
    
  • saw many strange faces in the crowd
    
  • don't let anyone unknown into the house
    

• not famous or acclaimed
  • an obscure family
    
  • unsung heroes of the war
    

• not known to exist
  • things obscurely felt surged up from unknown depths
    

• being or having an unknown or unnamed source
  • a poem by an unknown author
    
  • corporations responsible to nameless owners
    
  • an unnamed donor
    

• not known
  • an unknown amount
    
  • an unknown island
    
  • an unknown writer
    
  • an unknown source
    

Noun

• a variable whose values are solutions of an equation

• anyone who does not belong in the environment in which they are found

• an unknown and unexplored region
  • they came like angels out the unknown
    

Related words

• Synonyms: 
  strange , obscure , unsung , nameless , unidentified , unnamed , unknown quantity , stranger , alien , unknown region , terra incognita
• Antonyms: 
  known , acquaintance , friend