riffle shuffle noun 2verb 1forms 3 noun2 •A technique of shuffling a deck of playing cards by first separating the deck into two parts. •A permutation that models the outcome of a riffle shuffle; the operation of dividing an ordered set into two equal subsets and then alternately listing sequences of elements from each subset that have a common specified length. verb1 •To perform a riffle shuffle. formsriffle shuffled · riffle shuffling · riffle shuffles