riv ‧ u ‧ let /ˈrɪvjələt, ˈrɪvjʊlət/ BrE AmE noun [countable] written
[ Date: 1500-1600 ; Language: Italian ; Origin: rivoletto , from Latin rivulus , from rivus 'stream' ]
a very small stream of water or liquid
rivulet of
rivulets of rain running down the window