runnel
‘a rivulet; a small stream of water’
Lexical development traced from the Tamil root:
E. runnell, runnill < M.E. ryneil < O.E. rinelle, rynel < ryne ‘a flowing, a course, a watercourse,’ in the modern sense ‘small stream’ < ren ‘to run, flow’ < ri-ne-a- + el < ruh < rei-< Tamil aruvi