semitropical vs subtropical

semitropical

adj
  • Intermediate between temperate and tropical. 

subtropical

adj
  • Having some characteristics of a tropical cyclone but also some characteristics of an extratropical cyclone. 

  • Pertaining to the regions of the Earth further from the equator than the tropical regions. 

noun
  • A subtropical plant. 

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