subnormal vs unusable

subnormal

adj

  • denormal 

  • Less than normal. 

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. 

unusable

adj

  • Not usable. 

noun

  • Something that is not fit for use. 

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