A river in Beleriand translated by Christopher Tolkien as “stream flowing down from heights” (SI/Celon), a derivative of the root √KEL “flow”.
Conceptual Development: The name G. Celon first appeared in the Poetic and Mythological Words of Eldarissa from the 1910s, alongside other derivatives of the root ᴱ√KELE (PME/46), but it did not appear in the narratives until Silmarillion drafts from the 1930s (SM/330, LR/260). In The Etymologies, the word Ilk. celon “river” appeared, making it possible that Tolkien considered Celon to be an Ilkorin name at that time, though he first marked celon as Noldorin (Ety/KEL).
In Silmarillion revisions from the 1950s-60s, Tolkien became dissatisfied with this name, indicating that it was “too hackneyed a river-name”, and considered changing it to Limhír “clear/sparkling river” (WJ/337), but he never carried through with this change.