extreme vs tropic

extreme

adj
  • Of a place, the most remote, farthest or outermost. 

  • Drastic, or of great severity. 

  • Of sports, difficult or dangerous; performed in a hazardous environment. 

  • Excessive, or far beyond the norm. 

  • In the greatest or highest degree; intense. 

noun
  • A drastic expedient. 

  • The greatest or utmost point, degree or condition. 

  • Either of the two numbers at the ends of a proportion, as 1 and 6 in 1:2=3:6. 

  • Each of the things at opposite ends of a range or scale. 

tropic

adj
  • Of, or relating to the tropics; tropical. 

  • Having the quality of indirectly inducing a biological or chemical change in a system or substrate. 

  • Pertaining to, involving, or of the nature of a trope or tropes. 

  • Hot and humid. 

noun
  • Either of the two parallels of latitude 23°27′ north and south of the equator; the farthest points at which the sun can be directly overhead; the boundaries of the torrid zone or tropics. 

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