You use quadruple to indicate that something has four parts or happens four times. a quadruple murder. to increase and become four times as big or as high, or to make something increase in this way double, triple triple
a quantity that is four times as great as another increase fourfold; "His stock earning quadrupled"
a quantity that is four times as great as another increase fourfold; "His stock earning quadrupled" four times as great or many; "a fourfold increase in the dosage" having four units or components; "quadruple rhythm has four beats per measure"; "quadruplex wire