What is the meaning of quadruplicate?

noun

• Any four copies; any of four things that correspond to one another exactly.
  • usage: "it was signed in quadruplicate"

verb

• Reproduce fourfold.
  • usage: "quadruplicate the bill"

adjective

• Having four units or components.
  • usage: "quadruple rhythm has four beats per measure"; "quadruplex wire"
  • synonyms: quadruple, quadruplex, fourfold, four-fold