A stream flowing into the river Narog (S/122). Its initial element is ring “cold” (SA/ring), but the meaning of its final element is unclear.

Conceptual Development: This river was first named in the Lays of Beleriand from the 1920s as ᴱN. Ingwil (LB/68), and remained N. Ingwil in Silmarillion drafts from the 1930s (LR/262). It was changed to S. Ringwil in Silmarillion revisions from the 1950s-60s (WJ/197 note §112).