harvester vs plower

harvester

noun
  • A machine that gathers the harvest (harvests the crop). 

  • finnock (a young sea trout) 

  • A North American butterfly, Feniseca tarquinius, whose larvae eat aphids and are the only entirely carnivorous caterpillars in North America 

  • A program or algorithm that gathers data from a source. 

  • A type of heavy forestry vehicle employed in cut-to-length logging for felling, delimbing and bucking trees 

  • Any butterfly of the lycaenid subfamily Miletinae to which this belongs, which are all carnivores. 

plower

noun
  • One who plows; one who works land with a plow. 

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