Source : Webster's Revised Unabridged Dictionary (1913)

Rivulet \Riv"u*let\, n. [Earlier rivolet, It. rivoletto, a dim.
   fr. rivolo, L. rivulus, dim. of rivus a brook. CF. {Rival},
   {Rite}.]
   A small stream or brook; a streamlet.

         By fountain or by shady rivulet He sought them.
                                                  --Milton.

Source : WordNet®

rivulet
     n : a small stream [syn: {rill}, {run}, {runnel}, {streamlet}]