Celduin

noun. running river

cell (adj. “running, flowing”) + duin (“big and large river”)

celduin

place name. River Running

A river flowing from lake Esgaroth into the river Carnen, translated “River Running” (LotR/1046). It is most likely a combination of some form of the root √KEL “flow” and S. duin “duin”.

Elements

Word	Gloss
KEL	“flow (down or away), run (of water or rivers), go away, flow (down or away), run (of water or rivers), go away, [ᴹ√] run away especially downwards or at end; [ᴱ√] ooze, trickle”
duin	“(large) river, (large) river; [N.] water”