The definition of a rivulet is a very small stream.
(noun)A little stream of water in your back yard that is about 2 feet deep and 2 feet wide and that runs over some rocks down to the lake at the base of a hill is an example of a rivulet.
See rivulet in Webster's New World College Dictionary
noun
Origin: earlier rivolet < It rivoletto, dim. of rivolo, dim. of rivo, stream < L rivus, brook, stream: see rival
See rivulet in American Heritage Dictionary 4
noun
Origin:
Origin: Possibly from Italian rivoletto
Origin: , diminutive of rivolo, small stream
Origin: , from Latin rīvulus
Origin: , diminutive of rīvus, stream; see rei- in Indo-European roots
.Learn more about rivulet