nonpositive vs unpretty

nonpositive

adj
  • Not positive. 

  • Not positive; either zero or negative. 

noun
  • Any value that is not positive. 

unpretty

adj
  • Not pretty. 

verb
  • To make unpretty or less attractive 

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