ᴺS. [N.] ^raw¹ n. “bank (especially of a river)” (Category: Brook, Stream, River)
N. rhaw² n. “bank (especially of a river)” (Category: Brook, Stream, River)
A noun given as N. rhaw “bank, especially of a river” in The Etymologies of the 1930s, a derivative of the root ᴹ√RAB, also the basis for N. rham “wall” (Ety/RAMBĀ; EtyAC/RAMBĀ).
Neo-Sindarin: If adapted to Neo-Sindarin, this would would become ᴺS. raw as suggested in Hiswelókë’s Sindarin Dictionary (HSD), but I think it is better still to use the less ambiguous N. duirro for “river bank” given the other homonyms for S. raw.
Reference ✧ Ety/RAMBĀ ✧ rhaw “bank (especially of a river)”
|ᴹ√RAB² > rhaw||[rāba] > [rǭba] > [rouba] > [rouva] > [rauva] > [rauv] > [r̥auv] > [r̥au]||✧ Ety/RAMBĀ|