#1 fourfold s. [quadruple, four-fold] four times as great or many; "a fourfold increase in the dosage". wn
#2 fourfold r. [four times] by a factor of four; "the price of gasoline has increased fourfold over the past two years". wn
#3 fourfold s. [quadruple, quadruplicate, quadruplex, four-fold] having four units or components; "quadruple rhythm has four beats per measure"; "quadruplex wire". wn
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