copulae

Noun

copula (plural copulas or copulae)

1. 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.
   • I begin by arguing in section 2 that there are in fact at least two Celtic copulas, a grammatical copula that simply spells out tense and agreement, and a substantive copula formed on a lexically listed verbal stem.1994, Randall Hendrick, “8: The Brythonic Celtic copula and head raising”, in David Lightfoot, Norbert Hornstein, editors, Verb Movement, page 163

   Synonyms:

   linking verb, copular verb

2. The bond or relationship by which two things are combined into a unity.
   • The fact that in milk the copula or bond is exceedingly slight is evident from the spontaneous resolution of milk when left in a vessel, its resolution, namely, into cream—a white substance of comparative consistency,—and a sourish fluid; also from its ready resolution when, merely by motion, it is...1912, Emanuel Swedenborg, Alfred Acton, The Animal Kingdom, page 345
3. A function that represents the association between two or more variables, independent of the individual marginal distributions of the variables.
   • In 2000, David X. Li, a banker with a doctorate in statistics who was then at RiskMetrics, part of J. P. Morgan Chase, began using mathematical functions called Gaussian copulas to estimate the likelihood of corporations’ dying in unison.2009 March 10, Dennis Overbye, “Mathematical Model and the Mortgage Mess”, in New York Times
4. A device that connects two or more keyboards of an organ.
5. The act of copulation; mating.