From WordNet (r) 3.0 (2006) [wn]:
riffle
n 1: a small wave on the surface of a liquid [syn: ripple,
rippling, riffle, wavelet]
2: shuffling by splitting the pack and interweaving the two
halves at their corners
v 1: twitch or flutter; "the paper flicked" [syn: flick,
ruffle, riffle]
2: look through a book or other written material; "He thumbed
through the report"; "She leafed through the volume" [syn:
flick, flip, thumb, riffle, leaf, riff]
3: stir up (water) so as to form ripples [syn: ripple,
ruffle, riffle, cockle, undulate]
4: shuffle (playing cards) by separating the deck into two parts
and riffling with the thumbs so the cards intermix
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Riffle \Rif"fle\ (r[i^]f"f'l), n. [CF. G. riffeln, riefeln, to
groove. Cf. Rifle a gun.]
1. (Mining) A trough or sluice having cleats, grooves, or
steps across the bottom for holding quicksilver and
catching particles of gold when auriferous earth is
washed; also, one of the cleats, grooves, or steps in such
a trough. Also called ripple.
[1913 Webster]
2. A ripple in a stream or current of water; also, a place
where the water ripples, as on a shallow rapid. [Local, U.
S.]
The bass have left the cool depth beside the rock
and are on the riffle or just below it. --James A.
Henshall.
[Webster 1913 Suppl.]