copula vs vinculum

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. 

vinculum

noun
  • A ligament that limits the movement of an organ or part. 

  • A bond or link signifying union. 

  • A horizontal line over the top of some of the terms in an expression, indicating that that part of the calculation is to be done before other parts. 

  • Specifically, the horizontal line between the numerator and denominator in a fraction. 

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