subnormal vs unknown

subnormal

noun
  • A person whose abilities are less than normal. 

  • That part of the axis of a curved line which is intercepted between the ordinate and the normal. 

adj
  • denormal 

  • Less than normal. 

unknown

noun
  • A person of no identity; a nonentity 

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

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

adj
  • Not known; unidentified; not well known. 

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