erratic vs subnormal

erratic

noun
  • Anything that has erratic characteristics. 

  • A rock moved from one location to another, usually by a glacier. 

adj
  • Deviating from normal opinions or actions; eccentric; odd. 

  • Unsteady, random; prone to unexpected changes; not consistent. 

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. 

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