copula vs manacle

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. 

manacle

noun
  • A shackle for the wrist, usually consisting of a pair of joined rings; a handcuff; (by extension) a similar device put around an ankle to restrict free movement. 

  • A fetter, a restriction. 

verb
  • To confine with manacles. 

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