rou·leau \rüˈlō\noun (pluralrou·leaux \-ō(z)\ ; orrouleaus) Etymology: French, from Middle French rolel, diminutive of role roll — more at role : a little roll: as a.: a roll of coins put up in paper < held out rouleaux of pennies — Richard Llewellyn > b.: a group of red blood corpuscles resembling a stack of coins c.: a decorative piping or rolled trimming for women's clothing d.: a bundle of fascines used in groups in seige operations