Definitions of riffle:

• noun:   shuffling by splitting the pack and interweaving the two halves at their corners
• noun:   a small wave on the surface of a liquid
• verb:   shuffle (playing cards) by separating the deck into two parts and riffling with the thumbs so the cards intermix
• verb:   stir up (water) so as to form ripples
• verb:   twitch or flutter
• verb:   look through a book or other written material
• name:  A surname (rare: 1 in 50000 families; popularity rank in the U.S.: #6632)