polder vs swampland

polder

noun
  • An area of ground reclaimed from a sea or lake by means of dikes. 

verb
  • To reclaim an area of ground from a sea or lake by means of dikes. 

swampland

noun
  • Low-lying land that is regularly flooded; especially such land that is drier than a bog or a marsh. 

  • The set of effective low-energy physical theories that are not compatible with quantum gravity. 

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