nonpositive vs unnatural

nonpositive

adj

  • Not positive. 

  • Not positive; either zero or negative. 

noun

  • Any value that is not positive. 

unnatural

adj

  • Not natural. 

  • Going against nature; perverse. 

  • Not occurring in nature, the environment or atmosphere 

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