unknown in WordNet English dictionary

1. anyone who does not belong in the environment in which they are found
   stranger  alien  unknown 
   
2. an unknown and unexplored region
   "they came like angels out the unknown"
   unknown  unknown region  terra incognita 
   
3. a variable whose values are solutions of an equation
   unknown  unknown quantity 
   

1. being or having an unknown or unnamed source
   "a poem by an unknown author"; "corporations responsible to nameless owners"; "an unnamed donor"
   nameless  unidentified  unknown  unnamed 
   
2. not famous or acclaimed
   "an obscure family"; "unsung heroes of the war"
   obscure  unknown  unsung 
   
3. not known before
   "used many strange words"; "saw many strange faces in the crowd"; "don't let anyone unknown into the house"
   strange  unknown 
   
4. not known
   "an unknown amount"; "an unknown island"; "an unknown writer"; "an unknown source"
   unknown 
   
5. not known to exist
   "things obscurely felt surged up from unknown depths"
   unknown