colligation vs copulation

colligation

noun
  • A binding together. 

  • The formulation of a general hypothesis which seeks to connect two or more facts. 

  • The co-occurrence of syntactic categories, usually within a sentence. 

copulation

noun
  • The act of coupling or joining; union; conjunction. 

  • Sexual procreation between a man and a woman or transfer of the sperm from male to female; usually applied to the mating process in nonhuman animals; coitus; coition. 

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