copula vs coupling

copula

noun
  • A device that connects two or more keyboards of an organ. 

  • A word, usually a verb, used to link the subject of a sentence with a predicate (usually a subject complement or an adverbial), that unites or associates the subject with the predicate. 

  • A function that represents the association between two or more variables, independent of the individual marginal distributions of the variables. 

  • The act of copulation; mating. 

coupling

noun
  • A device that couples two things together. 

  • The property of physical systems that they are interacting with each other 

  • Sexual intercourse. 

  • Act of joining together to form a couple. 

  • The degree of reliance between two or more software modules. 

  • A connection between two electronic circuits such that a signal can pass between them. 

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