A stream in Beleriand (S/220), translated “Silver Foam” (SM/313) or “Silver Rain” (LR/140; Ety/ROS¹). This name is a combination of celeb “silver” and ross “foam” (SA/celeb, ros), so a more literal translation would be “Foam-silver” (WJ/151).
Conceptual Development: In early Silmarillion drafts from the 1930s, this name was once briefly written N. Celebrindon “Silver Bowl” (SM/313), but it mostly appeared in the form N. Celebros (SM/131, 313; LR/140). At its first appearance, its translation was already “Foam-silver” (SM/131), and it retained essentially the same meaning thereafter. This name also appeared in The Etymologies, which is the source of the derivation given above (Ety/ROS¹).
celeb (“silver”) + ros (“foam, rain”) The original form of ros is probably ross, with the final s dropped at the end of a polysyllable [HKF].